Spanbauer, Stanley J.
ASQC Quality Press, 1993
Buku Teks
Cass, James, author
New York, Harper & Row Publishers
Buku Referensi
Berkeley University of California Press 1968
Buku Teks
Barbeau, Joseph E.
Custom book program of northeastern University , 1985
Buku Teks
Frederick, Robert W.
USA Appleton 1947
Buku Teks