Ward, Robert
Philippines Summer Institute of Linguistic Translator Philippines Publishers 1968
Buku Teks
McKaughan, Howard P.
Institute of National Language, 1958
Buku Teks SO
London: Tiger Books International, 1994,
Buku Referensi
Oxford University Press, 1990
Buku Referensi
Lacey, Alan Robert
Routledge, 1986
Buku Referensi