Several archaeology books from the backlist at the Cotsen Institute at UCLA are available for free download:
An Archaeologist’s Guide to Chert and Flint – Luedtke 1992
The South American Camelids: An Expanded and Corrected Edition – Bonavio 2009
Maya Zooarchaeology: New Directions in Method and Theory – Emery 2004
A Conservation Manual for the Field Archaeologist – Sease 1994
About 20 more titles on Greek, Mesoamerican, and California archaeology are available from the Cotsen Institute of Archaeology Press.