Turko-Tatar was a common designation associated with academic Turkology in the 19th century.The term "Turko-Tatar" was used in scholarly works such as the Allgemeine Grammatik der Turko-tatarischen Sprachen by the Azeri scholar A. Kazem-bek (Kasan, 1839), or L.Z. Budagov’s Sravnitel’nïy slovar turetsko-tatarskix narechiy, i-ii (St. Petersburg, 1869-1871). By the early 20th century, many Turkic intellectuals were commonly using the term "Turko-Tatar" when referring to the entire Turkic world. This term was used in scholarship in this period by native Turkic scholars such as Zeki Velidi Togan in his Türk wä Tatar tarîxı (Qazan, 1912). "Turcotatar" is a former Library of Congress subject heading.