550,320 CASSENS BRETT J. Preventive medicine and public health / Brett J. Cassens. - 2 ed. - Baltimore [etc.] : National Medical Ser. from Williams and Wilkins ; Malvern : Harwal Publ. Co., [1992]. - XV, 497 s. j;26 cm (The National Medical Ser. for Independent Study) ISBN 0-683-06262-X