London: Her Majesty's Stationary office, 1987,
Buku Referensi
Tate, Merle W.
McMillan , 1955
Buku Teks
[publisher not identified], 1977
Buku Teks
Harrold, Ann
Library Association, 1986
Buku Referensi
Her Majesty's Stationery Office, 1987
Buku Referensi