A determinative of psd "back".
Walker
R E
RE
D000715:Anatomy / Q000193:education / Q000266:history; D018436:Ancient Lands / Q000208:ethnology; D004520:Education, Veterinary / Q000266:history; D049690:History, Ancient; D008373:Manuscripts as Topic / Q000266:history; D008374:Manuscripts, Medical as Topic / Q000266:history; D013904:Thoracic Vertebrae; D014730:Veterinary Medicine / Q000266:history