Não informado. Extension Folder. North Carolina State College of Agriculture and Engineering, Agricultural Extension Service.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Extension Folder. Raleigh, NC: North Carolina State College of Agriculture and Engineering, Agricultural Extension Service.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Extension Folder. North Carolina State College of Agriculture and Engineering, Agricultural Extension Service.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.