de Graaf-Roelfsema E, van der Kolk J H, Boerma S, van Haeringen H
Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, PO Box 80.152, 3508 TD Utrecht, The Netherlands.
Vet Rec. 2007 Aug 11;161(6):202-4. doi: 10.1136/vr.161.6.202.