Comparison of Morphine, meperidine, fentanyl, and sufentanil in balanced anesthesia: A double blind study. - Flacke,J.W.; Bloor,B.C.; Kripke,B.J.; Flacke,W.E.; Warneck,C.M.; van Etten,A.P.; Wong,D.H.; Katz,R.L. (Anesth. Analg., 1985)