Pickering, Thomas
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Buku Teks SO
Guzman, Caty
Times Editions, 2004
Buku Teks SO
Lancaster, F. Wilfrid
The Library Association, 1988
Buku Teks
Lancaster, F. Wilfrid
Uninersity of Illinois, 1993
Buku Teks
Lowen, Walter
Greystone Press, 1958
Buku Teks