Naumann, Naturgeschichte der Vögel Mitteleuropas. 3. Aufl. Neubearb. von G. Berg et al. Hrsg. von Carl R. Hennicke. (Naumann, Natural history of the birds of central Europe, 3rd Ed. Revised by G. Berg et al.; Edited by Carl R. Hennicke.) of 1905 or his earlier works.
This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 100 years or fewer.
This image was copied from wikipedia:sv. The original description was: Duvhök. http://www.biologie.uni-hamburg.de/b-online/birds {{PD}} {| border="1" ! date/time || username || edit summary |---- | 23 juli 2005 kl.15.06 || Knuckles || <nowiki>(Alla bil