https://bmcsurg.biomedcentral.com/articles/10.1186/1471-2482-14-35
https://bmcsurg.biomedcentral.com/articles/10.1186/1471-2482-14-37
https://bmcsurg.biomedcentral.com/articles/10.1186/1471-2482-14-38
https://bmcsurg.biomedcentral.com/articles/10.1186/1471-2482-14-39
https://bmcsurg.biomedcentral.com/articles/10.1186/1471-2482-14-36