Burnley, I. H., author
McGraw-Hill, 1976
Buku Teks
edited by Emrys Jones
Oxford University Press, 1975
Buku Teks
Knox, Paul, author
Longman, 1996
Buku Teks
Peterson, A.D.C., author
Gerald Duckworth, 1949
Buku Teks
Jones, Emrys, author
Oxford University Press, 1977
Buku Teks