The Universal Dictionary of Violin & Bow Makers is a widely cited reference work providing information on approximately 9,000 violin makers. The work is based on the extensive notes of violinist and composer William Henley (1874-1957). Henley had in his youth studied with August Wilhelmj, and later became a professor of composition and principal of the violin at the Royal Academy in London. Having played violins from many manufacturers, Henley sought to compile a comprehensive list evaluating violin and bow makers. After Henley's death in 1957, dealer Cyril Woodcock (1897–1980) completed and published the work based on Henley's unfinished notes. The work was first published in five volumes in 1959 and 1960, and republished in a single volume in 1973.