2Benzon HT, Wang HY, Belavic AM, et al. A Randomized double- blind comparison of epidural fentanyl infusion versus patient- controlled analgesia with morphine for postthoracotomy pain. Anesth Analg, 1993 ;76(2):316-322.
3Glass PSA, Estok P, Ginsberg BV, et al, Use of patient - controlled analgesia to compare the efficacy of epidural to intravenous fantanyl administration. Anesth Analg, 1992 ; 74 ( 2 ) :345 - 351.