Teo, Yi-Ling
Sweet & Maxwell Asia, 2011
Buku Teks
Berlmas, Genelle
Wadsworth and Cengage Learning, 2012
Buku Teks
Barendt, E. M.
Pearson, 2000
Buku Teks SO
edited and with a foreword by John Foley, Robert C. Lobdell and Robert Trounson
Mirror Press, 1977
Buku Teks
Praegar, 1976
Buku Teks