Herbazest - Comfrey - An in-depth explanation on comfrey's active ingredients, medicinal applications, and growing information. Wikipedia: Comfrey - Presents comfrey's medicinal use, cultivation, and a proper description. University of Maryland Medical Center - Provides an overview, precautions, and possible interactions. Supporting research is also available. College of Agricultural Sciences - Features a complete description from historical and biological points of view. NewCROP - Symphytum officinale - Brief article focused on the habitat and parts used of this herb. Calphotos: Comfrey - Photographs of this herb. Sloan-Kettering - Comfrey - Includes information on uses, constituents and mechanism of action. Loyola Medicine: Comfrey - Factsheet including warnings, side effects and interactions. Comfrey - Information and Recommended Uses - Diagnose Me - Comfrey