Warren-Smith, Neil
Oxford University Press , 1983
Buku Teks
Moncrieff, Gladys, author
Rigby, 1971
Buku Teks
Markus, John, 1911-, author
McGraw-Hill, 1994
Buku Referensi
edited by Abel Albet, Nuria Benach
Routledge, 2018
Buku Teks
Harris, Robert
Faber and Faber, 1984
Buku Teks