Digestive Enzymes for a Modern Diet - Jon Barron
Absorb More Nutrients with Digestive Enzymes - Dr. Axe - https://draxe.com/digestive-enzymes/
Digestive Enzymes Aren't Just for Digestion! Find Out the Powerful Cancer Fighting Benefits of Taking Pancreatic Enzymes - By William Snyder - http://bodyecology.com/articles/pancreatin-digestive-enzymes-cancer-fighting-benefits.php
Lopez, D.A., R.M. Williams, and K. Miehlke. Enzymes: The Fountain of Life. Salem, MA: The Neville Press, 1994.
Sankey, Mikio. Support the Mountain: Nutrition for Expanded Consciousness. Inglewood, CA: Mountain Castle Press, 2008.