Aerial surveys of waterbirds in Alaska, 1957-94 : population trends and observer variability /
Hodges, John I.
United States.National Biological Service.
[Washington, D.C.] : U.S. Department of the Interior, National Biological Service ; Denver, CO : May be obtained from the U.S. Geological Survey, Information Services ; Springfield, Va. : May be purchased from the National Technical Information Service,
[1996]
"August 1996."
Bibliographical references on p. 18 and continues on p. 24; no refs. between p. 19 and 23.
Includes bibliographical references (p. 18-24).
Anatidae
Bird populations