Baker, C.L.
MIT Press, 1989
Buku Teks
Radford, Andrew
Cambridge University Press, 2003
eBooks
Radfrod, Andrew
Cambridge University Press, 2004
Buku Teks
Shabrina Wulan Nursita
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2012
UI - Skripsi (Open)
edited by Marianne Hundt, Sandra Mollin, Simone E. Pfenninger
Cambridge University Press, 2017
Buku Teks