1. Numbering of primaries;Ashmole;Ibis 103a,1961
2. Observations on the breeding biology of the Hen Harrier in Orkney;Balfour;Bird Notes,1957
3. Iris colour in the Hen Harrier;Balfour;Bird Study,1970
4. Observations on the reproductive success in 26 nests of the Marsh Harrier Circus aeruginosus in Skane Province Sweden;Bengston;Ool. Rec,1967
5. An ecological study of some Minnesota Marsh Hawks;BreckenRidge;Condor,1935