The Automobile Association, 1990
Buku Referensi
compiled by S.K Baker
Oxford Publishing, 1984
Buku Referensi
Philip, George, author
George Philip and Son, 1983
Buku Referensi
Rapp, Stan, author
Erlangga, 1995
Buku Teks
Lenin, Vladimir I., author
Foreign Languages Publishing House , [date of publication not identified]
Buku Teks