A Non Silver Manual
Cyanotype, Brownprint, Palladium & Gum Bichromate with Instructions for Making Light-Resists Including Pinhole Photograpy.
Sarah Van Keuren Buy it from the author here
Alternative Processes Condensed
A Manual of Gum Dichromate and Other Contact Printing Processes Christina Anderson Another guide packed full of information from the author of "Experimental Photography Workbook".
Coming into Focus
John Barnier
Practical instructions on 20 processes. Highly recommended