Opus number developed other catalogue-number systems; among them the "Bach-Werke-Verzeichnis" (BWV-number), and the "Köchel-Verzeichnis" (K- and KV -numbers) with which are organised the works of Johann Sebastian Bach and Wolfgang Amadeus Mozart, respectively. In the classical period, the Latin word "opus" ("work", "labour") was used to identify, list, and catalogue a work of art. By the 15th and 16th centuries, the word "opus" was used by Italian composers to denote a specific musical composition, and by German composers for collections of music. In compositional practise, numbering musical works in chronological order dates from 17th century Italy, especially Venice. In common usage, the
Music history of the United States in the late 19th century - who often performed duets with Gottschalk while on tour - was a composer in his own right. Theodore Thomas (conductor) was considered to be a leading conductor during the 1880s and 1890s. Thomas too championed works by leading European composers. He also conducted works by leading U.S. composers. Today, the vast majority of 19th century U.S. composers are all but lost to history. This was also the era when women composers and African American composers started to see their music published in increased numbers. In the later decades of the 19th century, the music industry became dominated by a