TWIST, C. Encyclopedia of science: Life on earth fossils and human ancestors the basics of life. Volume IV. Macmillan Publishing Company.
Chicago-referens (17:e uppl.)TWIST, Clint. Encyclopedia of Science: Life on Earth Fossils and Human Ancestors the Basics of Life. Volume IV. Macmillan Publishing Company.
MLA-referens (8:e uppl.)TWIST, Clint. Encyclopedia of Science: Life on Earth Fossils and Human Ancestors the Basics of Life. Volume IV. Macmillan Publishing Company.
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