Simonds, John Ormsbee
McGraw-Hill, 1994
Buku Teks
edited by Peter Roberts and Hugh Sykes
Sage, 2003
Buku Referensi
edited by Peter Roberts, Hugh Sykes
Sage Publications, 2003
Buku Referensi
Newnes-Butterworths, 1979
Buku Teks
Powell, Kennetth
te Neues, 2000
Buku Teks