Currie, Lauchlin, author
Russell and Russell, 1968
Buku Teks
Bain, A.D., author
Penguin Books, 1970
Buku Teks
Hutchinson, Harry D., author
Appleton-Century-Crofts, 1967
Buku Teks
Hutchinson, Harry D., author
Meredith Corporation, 1971
Buku Teks
Schwartz, Bernard, author
Clarendon Press Oxford, 1972
Buku Teks