School Government Publishing Co., 1987
Buku Referensi
Buku Referensi
Indonesia. Direktorat Penelitian dan Pengabdian Kepada Masyarakat. Dirjen Dikti. Depdiknas
DIKTI, 2002
Buku Referensi
Williams, Gareth
PSI, [date of publication not identified]
Buku Teks
revised and updated by Sandy Norman
Library Association Publishing, 1999
Buku Teks