Williamson, E. M., By Okpako , D. T., & Evans , F. J. (1996). Pharmacological methods in phytotheropy: Research : selection, preparation and pharmacological evaluation of plant meterial. Wiley.
Chicago-viite (17. p.)Williamson, Elizabeth M., David T. By Okpako , ja Fred J. Evans. Pharmacological Methods in Phytotheropy: Research : Selection, Preparation and Pharmacological Evaluation of Plant Meterial. New York: Wiley, 1996.
MLA-viite (9. p.)Williamson, Elizabeth M., et al. Pharmacological Methods in Phytotheropy: Research : Selection, Preparation and Pharmacological Evaluation of Plant Meterial. Wiley, 1996.
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