Porter, Lindsay
Porter Publishing, 1995
Buku Referensi
Balaguru, Perumalsamy N.
Taylor &Fransic, 2009
Buku Teks
Caldarone, Michael A.
Taylor & Francis Group, 2009
Buku Referensi
Somerville, George
Taylor and Francis, 2008
Buku Teks
edited by Susan Macdonald ; foreword by David Watt & Pater Swallow.
Blackwell Sience, 2003
Buku Teks