1. Populations of tits and goldcrests and their food supply in pine plantations;Gibb;Ibis,1960
2. Contribution to the food biology of tits, especially about storing of surplus food Part 1. The crested tit (Parus c cristatus L);Hafthorn;Kgl Norske Vidensk Selsk Skr,1954
3. Contribution to the food biology of tits especially about storing of surplus food. Part II. The coal tit (Parus a ater L);Hafthorn;K Norske Vidensk Selsk Skr,1956
4. Contribution to the food biology of tits especially about the storing of surplus food. Part III. The willow tit (Parus atricapillus L);Hafthorn;K Norske Vidensk Selsk Skr,1956
5. Food storage, territory and song in the thick-billed nutcracker;Swanberg;Proceedings of the 10th International Ornithological Congress,1951