https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0127-4
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0125-6
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0130-9
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0126-5
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0129-2