APA (7 वां संस्करण) प्रशस्ति पत्र
Pepperberg, I. M. (1999). The Alex studies: Cognitive and communicative abilities of grey parrots. Harvard University Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्र
Pepperberg, Irene M. The Alex Studies: Cognitive and Communicative Abilities of Grey Parrots. Cambridge, MA: Harvard University Press, 1999.
एमएलए (9वां संस्करण) प्रशस्ति पत्र
Pepperberg, Irene M. The Alex Studies: Cognitive and Communicative Abilities of Grey Parrots. Harvard University Press, 1999.
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