Mettem, Christopher J.
Spon Press, 2011
Buku Teks
Sparrow, John, 1906-
Published for the British Council and the National Book League by Longmans, Green, 1992
Buku Teks SO
editors, Rui Calcada, Raimundo Delgado, Antonio Campos e Matos
CRC Press, Taylor & Francis Group, 2009
Buku Teks
Taly, Narendra
McGraw-Hill, 1998
Buku Teks
by Rene Walther [and others]
Thomas Telford, 1999
Buku Teks