https://sukofamily.org/7-ways-to-fail-as-a-missionary/
http://blog.godreports.com/2014/05/missionary-died-thinking-he-was-a-failure-84-years-later-thriving-churches-found-hidden-in-the-jungle/
http://freshexpressionsus.org/2016/03/02/14-innovations-wesleys-mission-failures/
13 Challenges Foreign Missionaries Face