Working in the Cincinnati Zoo as part of a worldwide effort to support endangered animals, scientist Terri Roth succeeds in helping a pair of Sumatran rhinos reproduce, using techniques that can be used to help other rhinoceroses both in captivity and, indirectly, in the wild. Woven into the saga of Emi, Ipuh and their progeny is a thorough introduction to this intriguing mammal, which is, next to elephants, the largest land animal in the world. With clearly written text, detailed and well-reproduced photographs and helpful maps and charts, Carson and Uhlman describe the five rhinoceros varieties in the world today, including something of their background, their habits and habitats, their similarities and differences. (A “Rhino field guide” with fast facts is part of the backmatter.) Other members of the zoo team are shown supporting Roth’s work. The emphases on reproductive science and zoo work both make this an unusual addition to the admirable Scientists in the Field series, one that should be welcome in high-school as well as middle-school libraries. (glossary, suggested reading and websites, index) (Nonfiction. 10-16)