Lipson, Leslie, author
Prentice-Hall, 1954
Buku Teks
Beard, Charles A.
Vintage Books, 1957
Buku Teks
Mackenzie, W.J.M
Penguin books, 1978
Buku Teks
Friedmann, Wolfgang, 1907-1972, author
W. Van Hoeve, 1954
Buku Teks
Mackenzie, W.J.M
Penguin books, 1978
Buku Teks