Não informado. Extension bulletin. Purdue University, Department of Agricultural Extension.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Extension Bulletin. Lafayette, Ind: Purdue University, Department of Agricultural Extension.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Extension Bulletin. Purdue University, Department of Agricultural Extension.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.