Johnson, Ned K. <br/><br/>
Biosystematics of sibling species of flycatchers in the Empidonax hammondii - oberholseri - wrightii complex / 
by Ned K. Johnson. 
 - Berkeley ;  Los Angeles :  University of California Press,  1963. 
 - 79-236 p.  illus. ;  26 cm. 
 - University of California publications in zoology  v. 66, no. 2 .
<br/><br/>Bibliography: p. 216-220. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Empidonax.