Castleman, Michael. “The Healing Herbs.” Rodale Press. Emmaus, Pennsylvania. 1991. pp. 133-134.
Christopher, David & Gileadi, Cathy. “The School of Natural Healing 100 Herb Syllabus.” Christopher Publications. Springville, UT. 1996. pp.150-158.
Christopher, Dr. John R. “The School of Natural Healing.” Christopher Publications. Springville, UT. 1996. p. 592.
Dr. Duke's Phytochemical and Ethnobotanical Databases. www.ars-grin.gov/cgi-bin/duke/farmacy2.pl. 1992.
Duke, James A. Ph.D. “The Green Pharmacy.” Rodale Press. Emmaus, Pennsylvania. 1997.
Elizabeth's Essentials. www.btinternet.com/~essentials/comfrey.htm. Online. Date accessed: 04/28/00.
Griggs, Barbara. “Green Pharmacy, The History and Evolution of Western Herbal Medicine.” Healing Arts Press. Rochester, Vermont. 1997. pp. 47, 101-102.
Harris, Ben Charles. “Comfrey: What You Need to Know.” Keats Publishing, Inc. New Canaan, CT. 1982. p. 9.
Hills, Lawrence D. “Comfrey: Fodder, Food & Remedy.” Appendix I by Dr. D.B. Long, Ph. D., M.A. Universe Books, New York. 1976. pp. 235-236.
Hilton Comfrey Compress. www.hiltonherbs.com/compress.html. Online. Date accessed: 04/28/00.
Hobbs, Christopher. “German Translation of PZ 39 (135): 6-7, 97-98, Sept. 1990.” Health World Online. www.healthy.net/hwlibraryarticles/hobbs/pzpyrr05.htm. 1996. Date accessed: 04/28/00.
Ritchason, Jack N.D. The Vitamin and Health Encyclopedia. Woodland Publishing, Pleasant Grove, UT. 1996. p.48.
Sun Soap's Comfrey Products. www.merchantmall.com/stores/sunsoap. Online. Date accessed: 04/28/00.
Tenney, Louise, M.H. “Today's Herbal Health.” Woodland Publishing. Pleasant Grove, UT. 1997. pp. 61-62.
The AWWWsome Online Store. www.awwwsome.com/awwwsome/comfreycreme.html. Online. Date accessed: 04/28/00.
The Merck Index, Twelfth Edition. Merck & Co., Inc. Whitehouse Station, NJ. 1997.
Webb, Ginger. “Variability in Comfrey PA content.” HerbalGram No.38, winter 1998. Health World Online. www.healthy.net/library/journals/herbalgram/herbalgram38/resrev/comfrey.htm. 1998. Date accessed: 02/22/00.
Wren, R.C., F.L.S. “Potter's New Cyclopaedia of Botanical Drugs and Preparations.” The C.W. Daniel Company Limited. Saffron Walden, England. 1994. pp.87-88.
"Natural Healing with Herbs for a Healthier You"