Não informado. (2001). Annual Report of the Board of Directors of the Zoological Society of Philadelphia. Zoological Society of Philadelphia.
Čikaški stil citiranja (17. izdanje)Não informado. Annual Report of the Board of Directors of the Zoological Society of Philadelphia. Philadelphia, Pa: Zoological Society of Philadelphia, 2001.
MLA način citiranja (8. izdanje)Não informado. Annual Report of the Board of Directors of the Zoological Society of Philadelphia. Zoological Society of Philadelphia, 2001.
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