UMEA UNIV. MEDICAL DISS. N. S. Nr 92 540,193 TRUEDSON HAKAN Cholecystectomy with prophylactic intraperi toneal drain . Clinical studies of the dis- ­ charge, consequence and necessity of prophy-­ lactic drainage . Umea 1982 Univ. 4 ° s . 144 , il . + wkł. s . nlb . 2 Umea Univ . Medical Diss. n . s . nr 92 Akad. avhandling Univ . of Umea