1. Economics of higher welfare pig production. An independent scientific report commissioned by the RSPCA;Arnoult,2011
2. Some behavioural deviations in weaned domestic pigs: persistent inguinal nose thrusting, and tail and ear biting;Blackshaw;Animal Production,1981
3. Attitudes of Dutch pig farmers towards tail biting and tail docking;Bracke;Journal of Agricultural and Environmental Ethics,2013
4. Weighing goods: equality, uncertainty and time;Broome,1991
5. Busch ME, Wachmann H, Nielsen EO and Petersen HH 2004. Tail biting – can slaughter data be used to identify herds with a high prevalence? (In Danish: Halebid – Kan slagtedata anvendes til at identificere besætninger med høj forekomst?), Report: Meddelelse 643, Danish Pig Research Centre (PRC), Copenhagen, Denmark. Retrieved August 22, 2014, from http://vsp.lf.dk/Publikationer/Kilder/lu_medd/2004/643.aspx?full=1