Speciation and geographic variation in Black-tailed Gnatcatchers.

Washington D C: American Ornithologists' Union, 1987. Octavo, black and white photographs, maps, wrappers.
American Ornithologists' Union Monograph number 42.
Washington D C: American Ornithologists' Union, 1987. Octavo, black and white photographs, maps, wrappers.
American Ornithologists' Union Monograph number 42.