From Pavia to Rocroi

Albi de la Cuesta, Julio. De Pavía a Rocroi: los tercios de infantería española en los siglos XVI y XVII. [Madrid]: Balkan Ediciones, 1999.

A very interesting examination of the Spanish tercio from many different standpoints. I haven't had a chance to do more than skim it, but I've already found it quite useful in some respects. The table of contents is posted, so that you can get an idea of the author's coverage of the subject. The glossary particularly, though spare, is useful. There are no footnotes, and the bibliography is keyed to the chapters (not necessarily helpful, but it does at least give an idea of the foundation of the author's thoughts).