Claude E. Heaton (1946). "The History of Anesthesia and Analgesia in Obstetrics". Journal of the History of Medicine and Allied Sciences. 1 (4): 567–572. doi:10.1093/jhmas/1.4.567. PMID20278344.
Claude E. Heaton (1946). "The History of Anesthesia and Analgesia in Obstetrics". Journal of the History of Medicine and Allied Sciences. 1 (4): 567–572. doi:10.1093/jhmas/1.4.567. PMID20278344.