https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4141019/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4336003/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897696/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3895328/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3806918/
https://onlinelibrary.wiley.com/doi/abs/10.1111/epi.12320
https://www.ncbi.nlm.nih.gov/pubmed/24246947
https://www.ncbi.nlm.nih.gov/pubmed/25050924
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4013813/
https://link.springer.com/article/10.1007%2Fs11910-014-0476-2