Rouse, Biair
New York Twayne 1962
Buku Teks
Hammer, Ellen J.
Stanford University Press, 1954
Buku Teks
Eeden, Frederik van
W. Wersluys, [date of publication not identified]
Buku Teks
Maddala, G.S.
McGraw-Hill Book , 1989
Buku Teks
Kemp, Patrick S.
John Wiley & Sons, 1989
Buku Teks