Boyle and Harvey on the valves in the veins.
D000715:Anatomy / Q000266:history*; D001775:Blood Circulation; D002309:Cardiology / Q000266:history*; D004739:England; D006351:Heart Valves / Q000033:anatomy & histology; D049669:History, 16th Century; D049670:History, 17th Century; D006801:Humans; D014680:Veins / Q000033:anatomy & histology*