Simon, J.E., A.F. Chadwick and L.E. Craker. 1984. Herbs: An Indexed Bibliography. 1971–1980.
Commercial Production of Ginseng and Goldenseal—L.P. Stoltz
Alternative Crops Research in Virginia—Harbans L. Bhardwaj, Andy Hankins, Tadesse Mebrahtu, Jimmy Mullins, Muddappa Rangappa, Ozzie Abaye, and Gregory E. Welbaum
Phytomedicines as a New Crop Opportunity—Loren D. Israelsen
Sievers, A.F. 1930. The Herb Hunters Guide. Misc. Publ. No. 77. USDA, Washington DC.