Brown, P.J.
John Wiley & Sons, 1979
Buku Teks SO
Brown, P.J.
John Wiley & Sons, [Date of publication not identified]
Buku Teks SO
Soyinka, Wale
Fonta Paperback, 1965
Buku Teks
Crezee, Ineke H.M
John Benjamins Publishing, 2013
Buku Teks
Aho, Alfred V.
Addison-Wesley, 1976
Buku Teks SO