PNUD-OIT-OMS. Essential requirements of poison information centres. En: Guidelines for poison information centres. Their role in prevention and response to poisonings. Programa Internacional de Seguridad de las Sustancias QuĂ­micas. Ginebra: septiembre de 1988:18-27. Troutman WG, Wanke LA. Advantages and disadvantages of combining poison control and drug information centres. Am J Hosp Pharm 1983;40:1219-22. Kasilo OJ, Froese EH. A ten year review of the teaching hospital-based national drug and toxicology information service in Zimbabwe. J Clin Pharm Ther 1989;14:355-71. Watanable AS, Conner CS. How to conduct a systematic literature search. Principles of drug information services. A syllabus of systematic concepts. Hamilton, IL: Drug Intelligence Publications, 1978:51-87. Hirshman JL. Building a clinically oriented drug information service. En: Francke DE, Whitney HAK Jr. Perspectives in clinical pharmacy. Hamilton, IL: Drug Intelligence Publications, 1972:150-77. Skoutakis VA, Wood GC. Clinical toxicology service. En: McLeod DC, Miller WA, eds. The practice of pharmacy. Institutional and ambulatory pharmaceutical services. Cincinnati: Harvey Whitney Books, 1981:120-39. Vlasses PH. General medical clinical pharmacy service. En: McLeod DC, Miller WA, eds. The practice of pharmacy. Institutional and ambulatory pharmaceutical services. Cincinnati: Harvey Whitney Books, 1981:140-7.