1. Red Crossbill;Adkisson,1996
2. Relationship between weather conditions, crops of Siberian pine nuts, and irruptions of Siberian Nutcrackers Nucifraga caryocatactes macrorhynchos C.L. Brehm in Siberia and Europe;Ananin;Avian Ecol. Behav.,2009
3. The nomadic breeding of the Redpoll Acanthis flammea in 1979 in North Savo, Finland;Antikainen;Ornis Fenn,1980
4. Oklahoma bird life;Baumgartner,1992
5. Food profitability and the foraging ecology of crossbills;Benkman;Ecol. Monogr.,1987