"Hudson Taylor and China's Open Century" by A. J. Broomhall, Book Six: Assault on the Nine, London: Hodder and Stoughton and Overseas Missionary Fellowship, (p. 189), 1988.
Oswald Chambers (2010). “Christian Disciplines: Building Strong Christian Character through Divine Guidance, Suffering, Peril, Prayer, Loneliness, and Patience”, p.158, Discovery House