1. Anonymous (1995 ) Bird of Prey Persecution in Scotland in 1994 . Royal Society for the Protection of Birds, Sandy, Bedfordshire. 10 pp.
2. K. Aaris-Sorensen (1988 ) Danmarks Forhistoriske Dyreverden . Gyldendal, Copenhagen. 252 pp.
3. W.C Allee, O. Park, A.E. Emerson, T. Park, and K.P. Schmidt (1949 ) Principles of Animal Ecology W. B. Saunders, Philadelphia. 837 pp.
4. Corvid Density and Nest Predation in Relation to Forest Fragmentation: A Landscape Perspective