Colford, Betsy. "From Tangun to Jesus: Korea's Quest for a Perfect Society." 1983.
Sasaki, Tatsuo. "Forty Years Japanese Colonization of Korea and the Foundation for the Messiah: God's Will or Human Error?" 1994, 68 pp.
Stoertz, William. "Korean as the Future Ideal Universal Language." 1992, 273 pp.