https://bmcstructbiol.biomedcentral.com/articles/10.1186/s12900-015-0047-z
https://bmcstructbiol.biomedcentral.com/articles/10.1186/s12900-015-0048-y
https://bmcstructbiol.biomedcentral.com/articles/10.1186/s12900-015-0046-0
https://bmcstructbiol.biomedcentral.com/articles/10.1186/s12900-015-0049-x