These are books I've found helpful.

 

Printing on the Iron Handpress, by Richard-Gabriel Rummonds.  A tremendously useful book, very detailed. Indeed, the amount of detail was initially overwhelming, but as I work forward, I find it falls into place.  Still available new, both in hardback and softback.

Printing with the Handpress, by Lewis M. Allen.  Much less detailed than Rummonds, but also interesting. Originally printed in a limited edition by Allen on his handpress, we're lucky that it was reprinted by Van Nostrand Reinhold and is easily available in used copies.