Williangton, C. Oliver
D. Van Nostrand Co., 1956
Buku Teks
Wellington, C. Oliver
van Nostrand, Comp., Inc , 1960
Buku Teks
Gardner, Fred V.
McGraw-Hill, 1940
Buku Teks
Pyhrr, Peter A.
John Wiley & Sons, 1973
Buku Teks
Stedry, Andrew C.
Prentice-Hall, 1960
Buku Teks