Resnikoff, H.L.
Holt, Rinehart and Winston, 1973
Buku Teks
Parkinson, Claire L., author
G.K. Hall, 1984
Buku Teks
Toynbee, Arnold J., author
Oxford University Press, 1948
Buku Teks
Wallbank, T. Walter, author
Scott, Foresman, 1965
Buku Teks
Wallbank, T. Walter, author
Scott, Foresman, 1967
Buku Teks