1. https://pdfs.semanticscholar.org/dd1d/7dd7992ae67546b22744f1feaf5d63aa2b95.pdf
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6173035/
3. https://www.wjgnet.com/1948-9358/full/v10/i3/140.htm
4. https://www.hindawi.com/journals/joph/2010/608751/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3589218/