"Pyometra in Small Animal Theriogenology" by Margaret V. Root Kustritz (Chapter 13),Small Animal Theriogenology, 2nd Edition
"Pyometra: Diagnosis and Treatment Options" by Mary McLoughlin and Domenico Ventrella, Veterinary Clinics: Small Animal Practice, Volume 47, Issue 4, Pages 797-809
"Pyometra" by T. J. McCarthy, The Veterinary Clinics of North America: Small Animal Practice, Volume 40, Issue 5, Pages 1091-1105
"Pyometra" by Roberta Sartorelli, Veterinaria, Volume 34, Issue 3, Pages 13-23