Abel, W. (1980). Agricultural fluctuations in Europe from the thirteenth to the twentieth centuries. St. Martin's Press.
Lua i Stíl Chicago (17ú heag.)Abel, Wilhelm. Agricultural Fluctuations in Europe from the Thirteenth to the Twentieth Centuries. New York: St. Martin's Press, 1980.
Lua MLA (9ú heag.)Abel, Wilhelm. Agricultural Fluctuations in Europe from the Thirteenth to the Twentieth Centuries. St. Martin's Press, 1980.