https://human-resources-health.biomedcentral.com/articles/10.1186/s12960-016-0165-0
https://human-resources-health.biomedcentral.com/articles/10.1186/s12960-016-0170-3
https://human-resources-health.biomedcentral.com/articles/10.1186/s12960-016-0159-y
https://human-resources-health.biomedcentral.com/articles/10.1186/s12960-016-0166-z
https://human-resources-health.biomedcentral.com/articles/10.1186/s12960-016-0164-1
https://human-resources-health.biomedcentral.com/articles/10.1186/s12960-016-0167-y