It is obvious that physicians need objective and concise information on herbal medicines (Table 11.1, p. 72). Textbooks of pharmacognosy and phytotherapy, leading scientific journals, meetings and seminars are the main sources available. Although this multiplicity of information is available, most phytotherapists are unable to collect appropriate information required for the practice of rational phytotherapy. In general pharmacognosy textbooks provide basic principles and detailed descriptions of herbal drugs organized by chemical classes of active components. Phytotherapy textbooks include information on the therapeutic use of herbal medicines. They certainly are books of medicine but often superficially. Both cannot contain information about new herbal drugs.