John B. West, Why doesn't the elephant have a pleural space?, in News in Physiological Sciences: An International Journal of Physiology Produced Jointly by the International Union of Physiological Sciences and the American Physiological Society, vol. 17, aprile 2002, pp. 47–50. URL consultato il 24 novembre 2017.
Gary Ritchison, Bird Respiratory System, su people.eku.edu, Eastern Kentucky University. URL consultato il 24 novembre 2017 (archiviato dall'url originale il 10 marzo 2019).
worldcat.org
Campbell, Neil A., 1946-2004., Biology, 2nd ed, Redwood City, Calif, Benjamin/Cummings Pub. Co, 1990, pp. 834–835, ISBN0805318003, OCLC20352649.