Não informado. (2007). Report of the Penrose Research Laboratory. Zoological Society of Philadelphia.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Report of the Penrose Research Laboratory. Philadelphia, Pa: Zoological Society of Philadelphia, 2007.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Report of the Penrose Research Laboratory. Zoological Society of Philadelphia, 2007.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.