https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0150-5
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0153-2
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0151-4
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0156-z
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0154-1
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0145-2
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0152-3
https://bmcsurg.biomedcentral.com/articles/10.1186/s12893-016-0155-0