Contributions to West Indian ... 1996: t.p. (Robert Powell) p. 14 (Dept. of Natural Sciences, Avila College, Kansas City, Mo.)

Phone call to pub., 06-12-96 (Dr. Robert Powell; b. 08-17-48)

Peterson Field Guide to reptiles and amphibians of Eastern and Central North America, 2016: t.p. (Robert Powell) of cover

Biblioteca del congreso (Estados Unidos), 11 noviembre 2019: Catálogo electrónico http://bit.ly/33MViLX