Fries, Charles Carpenter
University of Michigan Press, 1951
Buku Teks SO
Ron White...[et al.]
Cambridge University Press, 1991
Buku Teks SO
Chinese University Press, 2001
Majalah, Jurnal, Buletin
Jesus Romero-Trillo
Springer, 2012
eBooks
Foreword by Wong Lian Aik
Center for English Language Communication. NUS, 2001
Buku Teks SO