Studies:
https://www.ncbi.nlm.nih.gov/pubmed/8484483
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918681/
https://www.ncbi.nlm.nih.gov/books/NBK217858/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3645155/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4314232/
https://www.ncbi.nlm.nih.gov/pubmed/17200216
https://www.ncbi.nlm.nih.gov/pubmed/29081120
https://ndb.nal.usda.gov/ndb/foods/show/2968
https://ndb.nal.usda.gov/ndb/foods/show/270
https://www.fruitsinfo.com/barberry-fruit.php
http://www.herbsorganic.co.za/pages/working%20on/buchu/buchu%20information.htm
https://www.ncbi.nlm.nih.gov/pubmed/17416295
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4665443/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3679539/
https://www.sciencedirect.com/science/article/pii/S1018364712000638
https://www.ncbi.nlm.nih.gov/pubmed/7938266
https://www.ncbi.nlm.nih.gov/pubmed/12544035