Gribbin, John
Penguin Books, 1997
Buku Teks SO
edited by Nicholas Brooke
Macmillan, 1978
Buku Teks SO
Powers, Alan
RIBA, 2009
eBooks
Fleischman, Richard
L'Arcaedizioni, 1996
Buku Teks SO
Summer Institute of Linguistics (Philippines) : Linguistic Society of the Philippines, 1981
Buku Teks SO