Ethnologue Report for Hausa
Information about where Hausa is spoken and the number of its speakers.
The Hausa Language - by Paul Newman
Write-up on a reference grammar of the Hausa language, by one of the top authorities in the field, and published by Yale University Press.
Teach Yourself Hausa
Introduction to the Hausa language, including the basics of its phonetics and grammar, and some sample sentences illustrating everyday conversation in the language.