Fowkes, Ben
Palgrave, 2002
Buku Teks SO
edited by Stanislaw Grodz, Gina Gertrud Smith
Brill, 2014
eBooks
Samers, Michael
Routledge, 2017
Buku Teks SO
O`Donnell, Mike
Longman, 1991
Buku Teks SO
Spoonley, Paul
Oxford University Press, 1990
Buku Teks SO