R. L. Trask 
The History of Basque [PDF ebook] 

Basque is the sole survivor of the very ancient languages of Western Europe. This book, written by an internationally renowned specialist in Basque, provides a comprehensive survey of all that is known about the prehistory of the language, including pronunciation, the grammar and the vocabulary. It also provides a long critical evaluation of the search for its relatives, as well as a thumbnail sketch of the language, a summary of its typological features, an external history and an extensive bibliography.