Ranny, Austin
Prentince-Hall, 1987
Buku Teks
Salisbury, Harrison E.
Atheneum, 1965
Buku Teks SO
Mead, W.R.
Hurst, 1993
Buku Teks SO
Jutikkala, Eino
Frederick A. Praeger, 1962
Buku Teks SO
Cook, Timothy E.
The University of Chicago Press, 1997
Buku Teks SO