Proceedings of the Symposium on Slavic cultures: Bulgarian Contributions to Slavic Cultures : an International conference dedicated to the celebration of the thirteen hundredth anniversary of the founding of the Bulgarian State, Columbia University in the City of New York, November 14, 1980 /
Department of Slavic Languages and the Institute on East Central Europe of Columbia University in the City of New York, the Center for Bulgarian Studies of the Bulgarian Academy of Sciences ; edited by Rado L. Lencek ... [et al.] 
. - Sofia : Sofia Press,  1983 
. - 205 p.  22 cm.