Não informado. (1949). Agricultural economics research. U.S. Department of Agriculture, Bureau of Agricultural Economics.
Citação do estilo Chicago (17ª ed.)Não informado. Agricultural Economics Research. Washington: U.S. Department of Agriculture, Bureau of Agricultural Economics, 1949.
Citação MLA (8ª ed.)Não informado. Agricultural Economics Research. U.S. Department of Agriculture, Bureau of Agricultural Economics, 1949.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.