Bulgarian Sign Language (in Bulgarian: "български жестомимичен език (БЖЕ)") is the language, or perhaps languages, of the deaf community in Bulgaria. Primary schools were established for the deaf. Russian Sign Language was introduced in 1910, and allowed in the classroom in 1945, and Wittmann (1991) classifies it as a descendent of Russian Sign. However, Bickford (2005) found that Bulgarian Sign formed a cluster with Slovak, Czech, Hungarian, Romanian, and Polish Sign.