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Duncan, I.J.H.; Slee, G.S.; Seawright, E.; Breward, J. (1989). "Behavioural consequences of partial beak amputation (beak trimming) in poultry". British Poultry Science. 30 (3): 479–488. doi:10.1080/00071668908417172. PMID2684349.
Gentle, M.J.; Hunter, L.N.; Waddington, D. (1991). "The onset of pain related behaviours following partial beak amputation in the chicken". Neuroscience Letters. 128 (1): 113–116. doi:10.1016/0304-3940(91)90772-l. PMID1922938. S2CID37075517.
Gentle, M.J.; Hughes, B.O.; Fox, A.; Waddington, D. (1997). "Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-d-old domestic chicks". British Poultry Science. 38 (5): 453–463. doi:10.1080/00071669708418022. PMID9510987.
Duncan, I.J.H.; Slee, G.S.; Seawright, E.; Breward, J. (1989). "Behavioural consequences of partial beak amputation (beak trimming) in poultry". British Poultry Science. 30 (3): 479–488. doi:10.1080/00071668908417172. PMID2684349.
Gentle, M.J.; Hunter, L.N.; Waddington, D. (1991). "The onset of pain related behaviours following partial beak amputation in the chicken". Neuroscience Letters. 128 (1): 113–116. doi:10.1016/0304-3940(91)90772-l. PMID1922938. S2CID37075517.
Gentle, M.J.; Hughes, B.O.; Fox, A.; Waddington, D. (1997). "Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-d-old domestic chicks". British Poultry Science. 38 (5): 453–463. doi:10.1080/00071669708418022. PMID9510987.
Gentle, M.J.; Hunter, L.N.; Waddington, D. (1991). "The onset of pain related behaviours following partial beak amputation in the chicken". Neuroscience Letters. 128 (1): 113–116. doi:10.1016/0304-3940(91)90772-l. PMID1922938. S2CID37075517.