Grzimek, Bernhard (2003–2004). Grzimek's animal life encyclopedia. Neil Schlager, Donna Olendorf, American Zoo and Aquarium Association (2nd ed.). Detroit: Gale. ISBN0-7876-5362-4. OCLC49260053.
1956-, Flannery, Tim F. (Tim Fridtjof) (2001). A gap in nature : discovering the world's extinct animals. Text Pub. ISBN1-876485-77-9. OCLC48951590. {{cite book}}: |last= has numeric name (help)CS1 maint: multiple names: authors list (link)