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..
Lua i Stíl Chicago (17ú heag.)Library of Congress. Federal Research Division agus 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.
Lua MLA (8ú heag.)Library of Congress. Federal Research Division agus 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.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.