Hay, Oliver P. The pleistocene of the Middle region of North America and its vertebrated animals. - Washington : Carnegie Institution, 1924. - 385 p. : il. ; 25,5 cm - Carnegie Inst. of Washington 322 A . Subjects--Topical Terms: PaleontologíaPaleozoologíaVertebrata Subjects--Geographic Terms: América del Norte Index Terms--Genre/Form: Libro Universal Decimal Class. No.: 566(7-11)