Library of Congress. Federal Research Division & Curtis, G. E. (1993). Bulgaria: A country study (2nd ed.). Federal Research Division, Library of Congress : For sale by the Supt. of Docs., U.S. G.P.O..
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रLibrary of Congress. Federal Research Division और Glenn E. Curtis. Bulgaria: A Country Study. 2nd ed. Washington, D.C.: Federal Research Division, Library of Congress : For sale by the Supt. of Docs., U.S. G.P.O., 1993.
एमएलए (8वां संस्करण) प्रशस्ति पत्रLibrary of Congress. Federal Research Division और Glenn E. Curtis. Bulgaria: A Country Study. 2nd ed. Federal Research Division, Library of Congress : For sale by the Supt. of Docs., U.S. G.P.O., 1993.
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