Morgan, Theodore, author
Prentice-Hall, 1956
Buku Teks
Brownlee, O.H. (Oswald Harvey), 1917-, author
Prentice-Hall, 1954
Buku Teks
Hardy, Charles O., author
Brookings Institution, 1940
Buku Teks
Metzler, Lloyd A.
W.W. Norton & Company Inc. , 1948
Buku Teks
Gupta, Syamaprasad, author
The Johns Hopkins University Press, 1977
Buku Teks