Routledge, 1997
Buku Teks
edited by Eric Delson, Ian Tattersall, John A. Van Couvering and Alison S. Brokks
Garland Publishing, 2000
Buku Referensi
Langdon, John H.
Springer International Publishing, 2016
eBooks
Pawson, Ivan G.
John Wiley & Sons, 1977
Buku Teks SO
Eckhardt, Robert B.
McGraw-Hill, 1979
Buku Teks SO