Sudaruk Leu. (1994) The study of essential and non-essential drug utilization of out-patients in university hospital, central hospital and general hospital in Songkhla in 1993. Mahidol University,:ม.ป.ท.Sudaruk Leu. 1994. The study of essential and non-essential drug utilization of out-patients in university hospital, central hospital and general hospital in Songkhla in 1993. ม.ป.ท.:Mahidol University,;Sudaruk Leu. The study of essential and non-essential drug utilization of out-patients in university hospital, central hospital and general hospital in Songkhla in 1993. ม.ป.ท.:Mahidol University, 1994. Print.