Travers, Kenneth J.
Laidlaw Brothers, 1987
Buku Teks
Brumfiel, Charles Francis, 1914-
Addison-Wesley, 1962
Buku Teks
Jurgensen, Ray C.
Houghton-Miffiln, 1983
Buku Teks
Shrode, Leroy W.
The Hayes School, 1968
Buku Teks
Melzak, Z.A.
John Wiley & Sons, 1983
Buku Teks