Potzger, J. E. and Friesner, Gladys M. Birds: Book one; birds: Book two; Birds: Book three; Potzger, J. E. and Margaret Esther Whitney. Insects and some of their relatives; Potzger, J. E. What tree is that? book 1; what tree is that? book 2; Friesner, Gladys M. and Marian J. Hill. Wild flowers of spring; wild flowers of summer and late autumn. Buffalo, New York: Kenworthy Educational Service. 64 p. each; $0.59 each