Hudson, R. A.
Cambridge , 1980
Buku Teks
edited by Ulrich Ammon, Norbert Dittmar, Klaus J. Mattheier
Walter de Gruyter, 1987
Buku Referensi
edited by Ulrich Ammon, Norbert Dittmar, Klaus J. Mattheier
Walter de Gruyter, 1988
Buku Referensi
edited by Oscar Uribe-Villegas
Mouton, 1977
Buku Teks
Wardhaugh, Ronald
Blackwell Publishers, 2002
Buku Teks