Appel, René
Edward Arnold, 1988
Buku Teks
Heine, Bernd
Cambridge University Press, 2005
Buku Teks SO
Cambridge University Press, 2009
eBooks
Appel, René
Amsterdam Academic Archive, 2005
Buku Teks SO
edited by Ralph Ludwig, Peter Mühlhäusler and Steve Pagel
Cambridge University Press, 2019
Buku Teks SO