Não informado. (1987). The Journal of Agricultural Economics Research. U.S. Department of Agriculture.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. The Journal of Agricultural Economics Research. Washington: U.S. Department of Agriculture, 1987.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. The Journal of Agricultural Economics Research. U.S. Department of Agriculture, 1987.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.