Books Desccribing Stamp Prining Methods (Old Or New)

I was looking for a philatelic book that describes the various printing methods used for stamps (old or new book)?

To be more precise, looking for any book that would describe methods and processes used for printing postage stamps (i.e. gravure method)

Many thanks for any guidance

Fundamentals of Philately by L. N. Williams illustrates a number of different printing processes and has a wealth of other philatelic useful information. The 2nd edition is available from the APS for $60 to non-members and $48.00 to members. The first edition can often be found on E-Bay for less. The first edition has better illustrations and slightly less information. The 2nd edition was produced by copying the photos in the first edition. At this time there is only one copy of the 2nd edition (2008 revised) for $32.50 plus shipping of $6.50.

Printing Postage Stamps by Line Engraving: Baxter, James H.

Postage Stamps in the Making: John Easton, F. J. Melville