Katrina Brown ... [et al.]
The Global Environment Facility, 1993
Buku Teks
Crystal, David, 1941-
Cambridge University Press , 2007
Buku Teks
Monika Unkel
Graduate School of Language and Culture, Osaka University, 2018
Artikel Jurnal
Levinson, Stephen C.
Cambridge University Press, 2004
Buku Teks
Kalbe, 2006
Buku Teks