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Buku Teks
Roberts, R.S., author
Elex Media Komputindo, 1994
Buku Referensi
Delson, Donn, author
Bradson Press, 1983
Buku Referensi
Cashmore, Ellis, author
Routledge, 1994
Buku Teks
Murphy, Raymond, author
Cambridge University Press, 1998
Buku Teks SO