Myint Swe Khine, editor
Springer, 2012
eBooks
David Collier, John Gerring, editor
Routledge, 2009
Buku Teks
Barnard, C. J.
Harlow Longman Scientific & Technical , 1993
Buku Teks
Midgley, Mary, author
Routledge, 2006
Buku Teks
Mey, Marc De
Dordrecht, 1982
Buku Teks