Here are several free e-Books on the Protestant Reformation made available by our friends at

History of the Reformation of the Sixteenth Century
by J. H. Merle D’Aubigne

The Necessity of Reforming the Church
by John Calvin

Life of Martin Luther
by Joel R Beeke

The Reformers and the Theology of the Reformation
by William Cunningham

Historical Theology
by William Cunningham

Dawn of the Reformation
by Herbert B Workman

William Farel: The Story of the Swiss Reformation
by Earl M Blackburn