https://www.ncbi.nlm.nih.gov/pubmed/11933141
https://www.ncbi.nlm.nih.gov/pubmed/17873849
http://www.tandfonline.com/doi/full/10.1080/14786419.2014.1002088
http://www.google.sr/patents/EP2395839A1?cl=en
http://www.webmd.com/vitamins-supplements/ingredientmono-946-grapefruit.aspx?activeingredientid=946&
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC88888/
https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072731/
http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1002564
http://www.webmd.com/drugs/2/drug-1632-142/lipase-protease-amylase-oral/digestive-enzymes-oral/details
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3217679/
http://onlinelibrary.wiley.com/doi/10.1111/j.1472-765X.1992.tb00668.x/abstract
http://onlinelibrary.wiley.com/doi/10.1111/j.1745-4514.2000.tb00715.x/abstract