• Area: Science, Engineering & Mathematics
• Program: Chemistry
• Type of Writing: Essay (Analytical, Interpretive)
• Type of Writing: Science (writing about science for professional or non-science readers)
• Course Level: 1000
• English Speaking Nativeness: Native
• Year: 2020
• Paper ID: SE&M.C.E.S.1.N.2.2.2181

Chemistry in Music

The violin is an instrument praised for its beauty in craftsmanship, but also its striking song bird qualities for the few who are able to command its voice. With a long history predating its symbolic European construction, it is believed to have evolved from string instruments found in the orient, such as the rabāb and rebec in the 15th century. Once migrating to the regions of Spain and France the instrument began to develop into the classic standard shape that would be introduced by luthier Andre Amati (b.1505-1577) of Cremona, Italy. And although Andre Amati is acknowledged as one of the luthiers responsible for this remarkable design and image of the violin family, it would be the works from master luthiers Antonio Stradivari (1644-1737) and Bartolomeo Guiseppe Guarneri, del Gesú (1698-1744) that would create violins with unduplicated characteristics and sound that continue to surpass standards of the modern ear. Due to the work of Stradivari and Guarneri many continue to wonder how these violins continue to keep audiences in awe. Was it the technique and dedication to detail implemented ? Or is it the result of the infamous stock of maple and spruce trees they were harvested and molded from? Alongside musical historians, many scientists infatuated with the idea of the ‘golden age’ of violins continue to measure and develop hypotheses that might explain these musical gifts or the mere myth of designed perfection.

It is not absolutely certain that one ancient instrument is responsible for the modern design of the violin, but it has been taken into great consideration that many string instruments may have played a role in the evolution of the violins timeless appearance. One of the earliest forms considered is the rabāb, a two or three string, membrane bellied pear or boat shaped instrument native to multiple regions, as observed in the various structural interpretations and materials used. As early as the 9th and 10th century the rebāb has been identified in the Middle East, Africa, Northern India, Central and Southeast Asia each defined by the common characteristic of a large metal spike that rest on the base of the instrument that is used as a perch for the body to rest on while it is played with a bow, deeming it the title of ‘spike fiddle’.

Through trade, exchange of cultures and territorial conquest the design of the Arabian rebāb is believed to be the basis for the Spanish rebec, also a 1-3 stringed instrument, that was tuned in fifths^[1] with a similar boat shaped body that was performed using two different positions of either resting the instrument on the arm or under the chin while playing the strings with a bow. This body position used by the performer is believed to have had a great influence on the standard body position used today while performing on the violin. Tuned within a similar range identified with the violin (treble clef), the rebac would mainly be utilized as an instrument for the performance of folk music of the Renaissance era. With composition and instrumentation changing to meet the demands of performances the rebac would be replaced by the viol.

The viol was introduced to the musical stage of the Renaissance and Baroque Eras of the 15th century, as a fretted stringed instrument that would be bowed. The design of the viol (also identified as viol da gamba or gamba) is similar in shape to that of a lute or small guitar with a flat body and sound holes in the shape of the letter c, rather than the appearance of the f shaped sound holes found in members of the violin family. The strings of the viol are housed in a region named the peg box, similar to that of the violin that could adjust the tension on the string influencing the pitch produced, but again rather than being tuned in fifths the viol was frequently “tuned in fourths with a major third in the middle” (Wikipedia). The position in which the viol is performed resembles that of the cello or its predecessor the rebac, being held upright and supported between the legs of the performer.

The shape and material used in the performance of the viol would progress over time to accommodate a fuller sound, as observed with the use of gut strings wound in copper metal, and with the increased elevation of the string from the fingerboard to provide greater resonance in sound with the installation of a bridge^[2]. Other distinct modification with the viol was the gradual change in the instruments shape with an increasing geometrical cut to the mid region of the instrument body, as well as, the changing shape to the sound holes (c shape to f shaped) provides the suggestive ideas for the basis of the violin families classic template.

Like the instruments that preceded the viol, it began to see a decline in stage presence due to the increased preference for the vibrant, bright and boisterous sound that would fill larger spaces, as observed by the instruments of the violin family. As the growing popularity of the violin took over performance halls, the viol maintained a solo presence with Baroque works from J.S. Bach, Telemann, and many others while continuing as an accompaniment role to vocalist into the 18th century.

The violin is believed to have taken center stage when famed Italian luthier, Andrea Amati (1525-1611) created the template of what would become the modern day violin, after spending many years crafting viols and rebecs. From the city of Cremona in Northern Italy, Andrea Amati would create a legacy with his violin making school, teaching his sons Antonio Amati (1560-1649) and Giularmo Amati (Hieronymus, 1562-1630)  the art of being a luthier. Continuing the tradition that would be responsible for establishing the standard of excellent work would be Nicoló Amati (1596-1684), son of Giularmo Amati. Nicoló Amati is believed to be the most accomplished luthier of the Amati family, continuing to enhance the template of the violin established by his grandfather gradually improving the sound and growing character of this stringed instrument. Opportunities for apprenticeship under the guidance of Nicoló Amati directly influenced the abilities and performance of young luthier’s attending the Cremona violin school, namely the works of Antonio Stradivari (1644-1737) and Andrea Guarneri (1626-1698).

Andrea Guarneri was an Italian luthier from the city of Cremona, who apprenticed at the Cremona school of violins alongside Stradivari. Although his works of 250 violins, 4 violas and 14 violoncellos are not greatly known, the works of his grandson Joseph Guanarious del Gesu (Bartolomeo Guiseppe Guaneri, 1698-1744) would generate notable recognition leaving the family name a legacy in the violin world. The construction of del Gesù’s instruments were not always regarded as desirable when compared to the meticulous works of Stradivari, with noticeable lack in attention to detail without the use of templates, and recognizable use of unrefined techniques performing freehanded work. Although regarded at times as subpar, the violin work of Guaneri found appreciation and recognition among ameteur performing musicians and traveling Gypsy’s, rather than those residing in the high courts of the aristocracy, who preferred the soft and delicate sound from Amati or Stradivari violins. By recognizing the population his violins served, it is believed that del Gesù focused his efforts constructing instruments that would project a sound well in highly populated large spaces, allowing for greater opportunities in artistic design, freedom, and experimentation.

Tarisio Fine Instruments and Bows, image by John Dilworth and Carlo Chiesa Jan 2015

With the formal education and apprenticeship del Gesu received under the guidance of Nicolò Amati, there is some consideration that the shape of the del Gesu’s instrument body and sound hole designs were influenced by the work of Giovanni Maggini (1580-1630), an Italian luthier of the Brescian school. The work of Giovanni Maggini is recognized to have “unusually large sound holes…[experimenting] to improve the tone quality” (Smithsonian). Similar characteristics can be observed in the work of del Gesu, as he was known to use the design of the top plate maintaining a low arch, like those of the Amati design, but also incorporate elongated f holes as seen in the works of Maggini. With a greater focus on sound projection it is believed that del Gesu focused his efforts to produce a violin that would harness the darker viola overtones for an increased projection of sound within the middle range for the violin.

On the other hand, the works of Stradivari are regarded as the superior construct of the violin. With ongoing critical analysis of templates used for skillful cuts that would mold these instruments, the work of Stradivari is still unknown. Frequently the construction of Stradivari’s work questions the thickness of the body, the proportions of how the thickness of the body was distributed, utilization of blocks and linings, placement of sounds holes and many other curious features that have become a secret. The shape of a Stradivari violin is often recognized for its smaller stature (353-355 mm), a common feature recognized by the makers within the Cremona School including del Gesu (350-356 mm). Other violin makers before and after the reign of Stradivari have been noted to have a body length slightly longer at 14.68 inch (Brecian School), establishing a common standard of 14 inches for a full length violin.

Another factor that is taken into great consideration for its influence on sound is the thickness of the wood used for the violin body. Stradivari is noted for his particular attention to detail using carefully drawn molds and templates to ensure that each instrument reflected specific measurements. A violin dated from 1672 is an example of early craftsmanship skills of Stradivari’s with greater thickness in the bodies, as observed in the following measurements “Back at centre 14/64, graduating to 5-6/64 at flanks; belly all over between 5/64 and 6/64”  (W. Henry Hall et al, p185). As Stradivari continued to develop his craft his work became more reflective to that of his predecessors, but also pushing his creative boundaries with the thickness in regions of the belly and flanks of the violin. This can be observed in the measurements of a violin produced by Stradivari in 1715 with the “Back at centre 10/64, graduating to 6/64 and 6/64 belly between 6/64 and 7/64”, and with a more extreme example observed in a violin produced in 1736 “Back, 9/64, graduating to 6/64; belly varies between ⅛ and 6/64” (W. Henry Hall et al. p185-186). This observation and growth of possibly uncalculated, yet precise change is said to be a reflection of the direct influence from his predecessors from both Brescian and Cremonese schools, but also from an evolution of practical experience from the many tested  methods utilized in efforts to gain ideal amplification of sound.

image provided by The Strad, 2020

At times criticized for pushing the limitations of thickness within the molds of the violin body, Stradivari was noted for placing particular detail to the linings and blocks assumed to provide supportive strength to the glued sides of the instrument. For these blocks Stradivari is known to have chosen the common Cremonese willow wood for its quality in light weight and strength. Other Cremonese luthiers are acknowledged for implementing this technique of Amatis and Brescian luthiers, but utilized pine as their choice material for these blocks. Recognized as a technique of 1800 Italian luthiers, the implementation of blocks was not only noted for its ability to enhance the strength and integrity of the instrument, but also allowed for greater vibrational resonance among the sides of the violin.

The most recognizable and defining feature of the violin is the f hole, which is mirrored on the front of the instrument belly, delicately framed by the indented curvature of the body. The sound holes carved from the bodies of Stradivari violins are designed with excellent skill, but oddly none of his designs are considered to be identical to one another, an element that prompts the question if this feature resulted in enhanced acoustics. The creative freedom exhibited by many Italian luthiers in their design of f holes can be observed in Stradivari’s work, as he would fix the position of the holes to a desired position with a compass and small template. This vital starting point allowed for the trace work of longitudinal lines, maintaining a traditional design that would provide the opening with the use of a knife and focused artistic eye. Various design sketches used by Stradivari suggest that each instrument created a template reflective of the instrument in construction. Similarly, the influential and possibly more extreme practices implemented by students of the Brescian violin school are reflected in Stradivari’s application. Many of the students at the time were encouraged by their master instructor to use their creative eye rather than a template drawn onto the body. This method allowed for greater artistic expression among luthiers, but at times could result in undesirable esthetics, as reflected in selective works of Joseph Guarnerius del Gesù.

The other great visible characteristic of Stradivari violins is the varnish applied as a protective layer to the wood, but also the finishing touch that has generated great myth or legend to the instrument’s acoustic qualities. There has been great speculation that Stradivari had a specific recipe that was only known to him, which to some extent is true. But many of the materials utilized that provided depth and color can still be found today. Many luthiers of Stradivari’s time implemented various proportions of gum (a varnish), oil and a colouring agent that was mixed, then applied in a manner believed to be best by the maker. The application of the varnish by Stradivari is noted for a uniform appearance among the observed flaws within the color or clarity. Much of the success in the application of varnish is said to be from the long lineage of lute makers from earlier periods, who developed the standards for material to be used such as the gums, oils and vegetable colors. These standards in materials not only demanded the highest quality, but also a great understanding in painting techniques that were most likely a direct result from knowledge obtained from painters who pioneered the art form.

Stradivari was not noticed for his individualized varnish until he began to work outside of the guidance or watchful eye of Amati. Moving away from the tones of yellow of his master, Stradivari incorporated tones of red with the use of “gum soluble in oil, possessing good drying qualities…” (W. Henry Hill, et al. p. 174). The gum used by Stradivari are said to have been a “solution of spirit…used for the groundwork or for filling up the pores of the wood” (p.174), suggesting that the varnish was one that possibly “consist[ed] of various resins dissolved in a solvent, usually alcohol” (Williamsburg Art Conservation, 2017). The use of ‘spirit’ could suggest how Stradivari was able to obtain a varnish with desired drying qualities, but also noted for creating possible challenges during the drying process as noted in correspondents between Stradivari and a significant patron.

“I beg you will forgive the delay with the violin, occasioned by the

            varnishing of the large cracks, that the sun may not reopen them…”

                                                                        (Stradivari letter translation)

“Compatirà la tardanza del violino perchè è stato la causa per la

            vernice per le gran crepate che il sole non le faccia apririe…”

                                                                                    (Stradivari letter)

This letter could indicate some of the challenges imposed by the hard, rapid films from alcohol based solvents, which resulted at times in films lacking durability that would crack. Other material such as the oils used to varnish the instruments provided a durable and protective layer, but often would result in lengthy drying times. Oil varnishes could have been accomplished with potentially an essential oil or fixed-oil varnish. The essential oil varnish is known to have used resins that would be dissolved in a solvent consisting of commonly turpentine. Essential oil varnish provides a tough,thick and durable finish unlike the fraile finish from spirit solvents. As well the fixed-oil varnish would use resins that would be dissolved in linseed oil in addition to turpentine. Noted for qualities to provide a stronger finish than that of the essential oil varnish, which would be desirable among craftsmen but often resulted in delayed completion of projects due to the lengthy dry times. This was observed to be the possible cause as noted in a  correspondence between Stradivari and another patron.

“I have not sent the violin sooner in consequence of having had to wait

continually for some one (to convey it to you)…”

 (Stradivari letter translation)

“Non ho mandato il violino più presto a causa d’aspettare qualche persona

sempre…”  (Stradivari letter)

This letter possibly implies the use of a fixed-oil, as it has been observed that the drying time for solvents with these agents can take up to several weeks. This is a result of a lack in evaporation of the solvents and the oil remaining within the film and polymerizing. Attempts to accelerate the drying process using fixed-oil varnish incorporated the application of heat, as well as heavy metals to catalyse the reaction.

There continues to be a great many questions concerning the recipe that Stradivari followed, because various causes could have been the result in chipping or lacking transparency from the finished film varnish. Ultimately the lightness and subtle color applied showcases all of the attractive features unique to the violin, but most importantly without diminishing the quality of tone. The methods and chemicals utilized in varnish applications gradually changed using solvents that would not result in tedious drying periods, no matter the conditions the instrument was exposed to (humid or dry environment). The increased use of more cost effective materials resulted in a commercialization era of violin production and death to “the spirit of artistic emulation” (p. 177) of Stradivari’s adolescence. During the 1850’s  French luthiers such as Jean-Baptiste Vuillaume (1798-1875) were determined to reinstitute the old practices of the Cremonese luthiers like Stradivari, demonstrating that the cost of oil based varnishes reflected the qualities most desired from the tone of the violin. Vuillaume believed that the varnish recipes used during the height of the Cremonese violins allowed for greater resonance, warmth and wood flexibility. Vuillaume stated “where the one we search for was abandoned and replaced by shellac-based varnishes mixed with other more or less flexible resins, with everything being dissolved in alcohol. We can understand that the luthiers were obliged to use varnishes that would dry in a maximum of eight days so that they could make violins as fast in the winter as in the summer, but these varnishes have no flexibility and become too hard when dry and choke up the tone of the violin.” (A. Dipper). Although the finishing touch of varnish continues to be a subject of debate and its potential influence of sound resonance, continued speculation questions the stock of wood these instruments were harvested from.

With all of the various factors to consider to be an influence on the work of masters such as Stradivari and del Gesù, few have been privileged to hold, let alone scientifically test the acoustic or sample the materials of these works of art. Biochemists such as Joseph Nagyvary have and continue to spend an extensive amount of time researching the materials utilized by Stradivari and del Gesu in hopes to find the answers that could reconstruct a violin of equal quality.  In one of Nagyvary’s studies he considers that the quality of wood used by Stradivari was a great influence in the overall sound produced. Nagyvary first defines that the structure of wood being a “composite material composed of the three polymers cellulose, hemicellulose and lignin” (Nagyvary) provided the basis for the natural flexibility found in wood. These structural characteristics were influenced by seasonal factors that define the cell wall integrity of the tree with each subsequent growth cycle. The summer months are responsible for the thinner cell wall structure resulting in a larger inner diameter of earlywood^[3], versus the secondary cell walls that form in addition to the initial cell wall during the winter months of latewood development. Suggested factors such as the ‘Maunder Minimum’ (1650-1715), a time when a reduction of sunspots resulted in an overall reduction in global temperature of .3 degrees centigrade has become suspect in the direct influence of minimal growth in latewood, increasing narrow growth rings potentially contributing to an increase in elasticity and vibrational characteristics of the violin. Scientists attempt to recreate this anomaly with the use of hemicellulases to degrade secondary walls of the hemicellulose present in materials available today in hopes to replicate these characteristics.

Chemical distinctions between Stradivari’s maple and modern tonewood, Hwan-Ching Tai, et al. 2017

Additional factors that are believed to be a significant contributor to the resonant characteristics of these violins is the application of insecticides and fungicides used to protect the wood from problematic pests such as woodworm and fungal decay. Woodworm infestations continue to be the result of Anobium punctatum, a type of wood eating beetle that lays its eggs on the surface of dead timber where the bark is no longer present. Once the eggs hatch the young beetles that were once larvae will emerge feasting on the surrounding environment, leaving a small hole of 1-2mm on the wood surface resulting in visible damage. To preserve the intended maple or pine available trace elements such as boron had been identified within samples from Stradivari and Guarneri, suggesting the application of insecticides. Other trace elements that have been identified in a 1717 Stradivari and 1735 Guarneri through EDS (energy dispersive X-ray spectroscopy) suggest techniques of treating or soaking the wood prior to harvest or distribution to master luthiers. This treatment was most likely a result of loggers protecting their investments for intended sale. So would it potentially be appropriate to assume that the modifications implemented after harvest were a result of the loggers applying an insecticide, or the local alchemist that would have concocted the solvents necessary to prevent woodworm?

With the suggestion that loggers and local alchemists having influence on the maple sculpted by the hands of Stradivari, there remains strong implication that he implemented a practice and forgotten tradition in treating the wood. On going analysis of protected and limited available samples of Stradivari wood have been exposed to C NMR spectroscopy, synchrotron X-ray diffraction and thermogravimetric analysis. Each of these calculated observations and measurements have shown characteristics of the wood to have reduced moisture content, decomposition of hemicellulose and signs of lignin oxidation after 300 years. Additional analysis have identified other trace elements to include Al, Ca, Cu, Na, K and Zn suggesting the possibility of chemical treatments via soaking, but also stressing the significant difference in the maple available during the ‘golden age’ of violin making versus the maple of today. Although there are no published notes from luthiers of the 18th and 19th centuries on violin making and mineral treatments, it can be observed that the technique of soaking the wood has been noted to make measurable effects on the vibrational qualities of wood.

Chemical distinctions between Stradivari’s maple and modern tonewood, Hwan-Ching Tai, et al. 2017

Although there is great desire to replicate what has been deemed the ideal voice of the violin, perhaps in the extensive biographical research of Stradivari’s life work the Hill’s capture the most important lesson is that “If we of modern times really wish to regain the knowledge possessed on this subject by the old makers, we must begin by retracing our steps. Leaving behind us conditions more resembling those of the period when the grand old masters of violin-making flourished” (W. Henry Hill, et al. p.178). With profound expertise and an obsessive eye for design Stradivari accomplished recognition of excellence within the high courts of society. And although the name Joseph Guanarious del Gesu did not obtain as much recognition as his competition, he was still able to produce instruments that rank with superiority among performers and listeners alike. Just as beauty is within the eye of the beholder, perhaps members of the audience should remember to focus their attention on the beauty that sings to their ears no matter the craftsmen.

Tarisio Fine Instruments and Bows, image by John Dilworth and Carlo Chiesa January 2015

Notes

^[1] Fifths: is the interval from first to the last of five consecutive notes in a diatonic scale.

^[2] Bridge: the part of a stringed instrument that holds the strings in place and transmits their vibrations to the resonant body of the instrument.

^[3] Earlywood: The part of the wood in a growth ring of a tree that is produced earlier in the growing season. The cells of early wood are larger and have thinner walls than those produced later in the growing season.

Works Cited

Dipper, Andrew. “A Look at Parisian Violin Makers’ Approach to Varnish”. String Magazine. OCT 7, 2016. https://stringsmagazine.com/a-look-at-parisian-violin-makers-approach-to-varnish/ visited APR. 7, 2021.

Hill, W. Henry. and Arthur F. Hill, and Alfred E. Hill. “Antonio Stradivari: His Life and Work (1644-1737). Dover Publications. 1963.

Nagyvary, Joseph.  “The Stradivarius Mystique”. Joseph Nagyvary 2001-2008. http://www.nagyvaryviolins.com/mystique_and_intrigue_of_the_stradivarius.html visited FEB. 2021.

Smithsonian Division of Music, Sport and Entertainment.  “Giovanni Paolo Maggini”. SEPT 1997. https://www.si.edu/spotlight/violins/maggini visited MAR 2021

Snyder, Thomas A. “A BRIEF ESSAY ON HISTORIC FURNITURE VARNISHES AND RESINS”. 2017. http://www.williamsburgartconservation.com/historic-varnishes-and-resi.html visited MAR. 2021.

Wikipedia. “Fifths Tuning”. Wikimedia Foundation. 18 October 2020.  https://en.wikipedia.org/wiki/Fifths_tuning visited MAR 2021.

Images Cited

Dilworth, John and Carlo Chiesa. Tasario: Fine Instruments and Bows. January 13, 2015. https://tarisio.com/cozio-archive/cozio-carteggio/guarneri-del-gesu-part-iii-1740-1744/

Hwan-Ching Tai, Guo-Chian Li, Shing-Jong Huang, Chang-Ruei Jhu, Jen-Hsuan Chung, Bo Y.

Wang, Chia-Shuo Hsu, Brigitte Brandmair, Dai-Ting Chung, Hao Ming Chen, and Jerry Chun Chung Chan. “ Chemical Distinctions Between Stradivari’s Maple and Modern Tonewood”. Edited by Jerrold Meinwalk, Cornell University. November 21, 2016. PNAS January 3, 2017. https://doi.org/10.1073/pnas.1611253114 visited FEB 2021.

The Strad. Newsquest Specialist Media Limited. 2020. https://www.thestradshop.com/store/thestrad/antonio-stradivari-1694-benecke-violin/

References

Choi, Charles. “Secrets of the Stradivarius: An Interview with Joseph Nagyvary”. Scientific American. June 10, 2002. https://www.scientificamerican.com/article/secrets-of-the-stradivari/ visited April 2021

Hill, W. Henry. and Arthur F. Hill, and Alfred E. Hill. “Antonio Stradivari: His Life and Work (1644-1737)”. Dover Publications. 1963.

Hwan-Ching Tai, Guo-Chian Li, Shing-Jong Huang, Chang-Ruei Jhu, Jen-Hsuan Chung, Bo Y. Wang, Chia-Shuo Hsu, Brigitte Brandmair, Dai-Ting Chung, Hao Ming Chen, and Jerry Chun Chung Chan. “Acoustic Evolution of Old Italian violin from Amati to Stradivari”. Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan; Instrumentation Center, National Taiwan University, Taipei 10617, Taiwan; Private address, 86567 Hilgertshausen-Tandern, Germany; Chimei Museum, Tainan 71755, Taiwan. Jan 3. 2017. First Published December 19, 2016. https://doi.org/10.1073/pnas.1611253114 visited February 2021.

Hwan-Ching Tai, Guo-Chian Li, Shing-Jong Huang, Chang-Ruei Jhu, Jen-Hsuan Chung, Bo Y. Wang, Chia-Shuo Hsu, Brigitte Brandmair, Dai-Ting Chung, Hao Ming Chen, and Jerry Chun Chung Chan. “ Chemical Distinctions Between Stradivari’s Maple and Modern Tonewood”. Edited by Jerrold Meinwalk, Cornell University. November 21, 2016. PNAS January 3, 2017. https://doi.org/10.1073/pnas.1611253114 visited FEB 2021.

Nagyvary, Joseph. “Investigating the secrets of the Stradivarius”. JAN 3. 2005Royal Society of Chemistry 2021. https://edu.rsc.org/feature/investigating-the-secrets-of-the-stradivarius/2020139.article Visited April 2021.

Roth, Klaus. “Chemical Secrets of the Violin Virtuosi – Part 2”. ChemViews Magazine. July 3 DOI: 10.1002/chemv.201200057 https://www.chemistryviews.org/details/ezine/2067505/Chemical_Secrets_of_the_Violin_Virtuosi__Part_2.html visited Febuary 2021

Santa Maria Bouquet, Jonathan. “The Lute”: The Heilbrunn Timeline of Art History Essays. New York: The Metropolitan Museum of Art, 2000. https://www.metmuseum.org/toah/hd/lute/hd_lute.htm April 2010. visited March 2021

Vienna Symphonic Library. “Violin: History”. 2002-2021. https://www.vsl.co.at/en/violin/history visited March 2021.

Wikipedia. “Andrea Amati”. 30 January 2021.https://en.wikipedia.org/wiki/Andrea_Amati Visited February 2021.

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Wikipedia. “Viol”. 13 April 2021.  https://en.wikipedia.org/wiki/Viol visited March 2021.