Mager, N.H., author
William Morrow and Co., 1982
Buku Referensi
Keegel, John C.
Regents Publishing Company, 1976
Buku Teks
Choe, Kyong-bong, 1965-, author
Chaek kwa Hamkke, 2006
Buku Referensi
Anderson, Wallace L., author
Holt, Rinehart and Winston, 1966
Buku Teks
Oppenheim, Peter K.
Prentice-Hall, 1976
Buku Teks