European Pharmacopoeia foot-and-mouth disease vaccine potency testing in cattle: between test variability and its consequences., Goris, N, Merkelbach-Peters P, Diev V I., Verloo D, Zakharov V M., Kraft H-P, and De Clercq Kris , Vaccine, 2007 Apr 30, Volume 25, Issue 17, p.3373-9, (2007)