5361/the_normal_canine.htm[νεκρός σύνδεσμος], Dr B Eilts, Louisiana State University School of Veterinary Medicine, "Normal Canine Reproduction" retrieved 10 April 2013
[1]Αρχειοθετήθηκε 2013-04-21 στο Wayback Machine., Dr B Eilts, LSU Veterinary Medicine, "The Normal Canine Estrous Cycle" retrieved 10 April 2013.