Pounds, Norman J. G. Eastern Europe. Chicago: Aldine, 1969.
"The Professional Gap," East Europe, X, No. 10, October 1969, 40.
Rizov, Alexander (ed.). Bulgaria, A Survey. Sofia: Foreign Languages Press, 1965.
Rose, Harold. Your Guide to Bulgaria. London: Alvin Redman, 1964.
Rothschild, Joseph. Communist Eastern Europe. New York: Walker, 1964.
Rusinov, Spas. Bulgaria: A Survey. Sofia, Sofia Press, 1969.
Sanders, Irwin T. Balkan Village. Lexington: University of Kentucky Press, 1949.
Schöpflin, George (ed.). The Soviet Union and Eastern Europe. New York: Praeger, 1970.
Severin, R. Keith. "Bulgaria's Agricultural Economy in Brief," U.S. Department of Agriculture, Economic Research Service. Foreign Agriculture, (ERS-Foreign 136.) September 1965, 1-11.
Sharp, Samuel L., and Fedlam, Fruzsina H. The Soviet Union and Eastern Europe, 1972. (The World Series.) Washington: Stryker-Post Publications, 1972.