1. Early weaning and cage rearing of piglets: influence on behaviour;Algers;Zentralblatt für Veterinärmedizin, Reihe A,1984
2. Appleby, M.C., Weary, D.M., Taylor, A.A., Illmann, G., in press. Vocal communication in pigs: who are piglets screaming at? Ethology.
3. The effect of age at weaning and post-weaning environment on the behaviour of pigs;Bøe;Acta Agric. Scand., Sec. A. Animal Sci.,1993
4. Bowlby, J., 1969. Attachment and Loss, Vol. 1, Attachment. Hogarth Press, London.
5. Connor, M.L., 1993. Recommended Code of Practice for Care and Handling of Pigs. Agriculture Canada, Ottawa.