Hausa has two level tones which may combine to
form a falling tone. Vowels may occur long or short. For
many speakers the diphthong /ai/ is pronounced /e:/ in
most positions. Palatalized velars do not contrast with
plain velars before front vowels /i,e/ nor do labialized
velars contrast before back vowels /u,o/.

Abraham, R.C. 1934. The Principles of Hausa vol. 1.
Government Printer, Kaduna.

Abraham, R.C. 1959. The Language of the Hausa People.
University of London Press Ltd., London.

Abraham, R.C. Hausa Literature and the Hausa Sound System.
University of London Press, London.

Brauner, S. and Ashiwajn, M. 1966. Lehrbuch der
Hausa-Sprache. Max Hueben Verlag, Munich.

Greenberg, T.H. 1941. Some problems in Hausa phonology.
Language 17: 316-323.

Hodge, C.T. 1947. An Outline of Hausa Grammar (Language
Dissertation 41). Linguistic Society of America,
Baltimore.

Hodge, C.T. and Umaru, I. 1963. Hausa Basic Course.
Foreign Service Institute, Washington D.C.

Kraft, C.H. 1963. A Study of Hausa Syntax, Vol.I.,
Structure. Department of Linguistics, The Hartford
Seminary Foundation, Hartford, Connecticut.

Kraft, C.H. and Kirk-Greene, A.H.M. 1973. Hausa. Teach
Yourself Books, London.

Kraft, C.H. and Kraft, M.G. 1973. Introductory Hausa.
University of California Press, Berkeley.

Taylor, F.W. 1959. A Practical Hausa Grammar. Clarendon
Press, Oxford.