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Weitzenbürger, D.; Vits, A.; Hamann, H.; Distl, O. (October 2005). "Effect of furnished small group housing systems and furnished cages on mortality and causes of death in two layer strains". British Poultry Science. 46 (5): 553–559. doi:10.1080/00071660500303206. ISSN0007-1668. PMID16359107. S2CID10933379.
Weitzenbürger, D.; Vits, A.; Hamann, H.; Distl, O. (October 2005). "Effect of furnished small group housing systems and furnished cages on mortality and causes of death in two layer strains". British Poultry Science. 46 (5): 553–559. doi:10.1080/00071660500303206. ISSN0007-1668. PMID16359107. S2CID10933379.
van Hoek, Caroline S.; Ten Cate, Carel (January 1998). "Abnormal Behavior in Caged Birds Kept as Pets". Journal of Applied Animal Welfare Science. 1 (1): 51–64. doi:10.1207/s15327604jaws0101_5. ISSN1088-8705. PMID16363987.
Huber-Eicher, B; Sebö, F (November 2001). "The prevalence of feather pecking and development in commercial flocks of laying hens". Applied Animal Behaviour Science. 74 (3): 223–231. doi:10.1016/s0168-1591(01)00173-3. ISSN0168-1591.
Weitzenbürger, D.; Vits, A.; Hamann, H.; Distl, O. (October 2005). "Effect of furnished small group housing systems and furnished cages on mortality and causes of death in two layer strains". British Poultry Science. 46 (5): 553–559. doi:10.1080/00071660500303206. ISSN0007-1668. PMID16359107. S2CID10933379.