Não informado. (2001). Annual Report of the Board of Directors of the Zoological Society of Philadelphia. Zoological Society of Philadelphia.
Lua i Stíl Chicago (17ú heag.)Não informado. Annual Report of the Board of Directors of the Zoological Society of Philadelphia. Philadelphia, Pa: Zoological Society of Philadelphia, 2001.
Lua MLA (8ú heag.)Não informado. Annual Report of the Board of Directors of the Zoological Society of Philadelphia. Zoological Society of Philadelphia, 2001.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.