Artikel Jurnal
Kraemer, Sieverts & Partners ; English translation by James L. Ritchie
McGraw-Hill , 1977
Buku Teks
by Robert B. Handfield [and others]
South Western Cengage Learning, 2011
Buku Teks
Montgomery, Robert L., author
Little, Brown, 1962
Buku Teks
Whitehead, Alfred North, 1861-1947, author
The New American Library, 1933
Buku Teks