Author: Johnson, Ned K.
Title: Biosystematics of Sibling species of Flycatchers in the Empidonax Hammondii - Oberholseri - Wrightii complex.
Description: Berkeley, 1963. 78-220 pp. 6 b./w. plts. Softcover. (Univ. of Calif. Publ. 66/2).

Keywords: Birds Vogels