https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0157-y
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0162-1
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0159-9
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0158-x
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0160-3
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0161-2
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0164-z
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0163-0