Weston, Paul B., author
Prentoce-Hall, 1981
Buku Teks
Wright, Samson
Oxford University Press, 1931
Buku Referensi
Heragu, Sunderesh S., author
Sunderesh S., 2016
Buku Teks
Press, Frank, author
W.H. Freeman and Company, 1986
Buku Referensi
Weston, Paul B., author
Prentice-Hall, 1977
Buku Teks