The genera dermacentor and otocentor (Ixodidae) in the United States, with studies in variation / by R.A. Cooley.

Washington : G. P. O., 1938.

v, 89 pages, 30 unnumbered leaves of plates : illustrations (some color) ; 23 cm

At head of t.p.: U. S. Treasury Department, Public Health Service. National Institute of Health Bulletin No. 171 (continuation of Hygienic Laboratory Bulletin Series), December, 1938

Includes bibliographic references