Leading the pack in the latter is Dick Arentz's Platinum and Palladium Printing, Second Edition. While the first edition was a very good text, the second edition is that rarity of where the improvements are welcome and justify purchasing that second edition even if you own the first.
What makes a great textbook on an alternative printing method? A much needed introductory chapter, that appears in the second edition, whose purpose is to get you to that first print. It may not be the best print you ever made, but it certainly simplifies the detailed discussion of the process once you make it from start to finish. Everything becomes very clear.
Another point that makes a textbook useful is that the material can be applied to related processes. The comprehensive chapter on paper, covering solutions to common problems associated with using a particular paper for platinum and palladium printing, surveying some major available papers, and describing their artistic properties is valuable for many other processes. The material on sensitometry is applicable to all photographic processes. Similarly the discussion on UV light sources, coating methods and equipment, appendix on digital negatives, and other material will prove valuable to all your alternative photographic endeavors!
Arentz writes in a crisp, no nonsense style with the rare humorous remark (maybe someday I should write a blog suggesting The Elements of Style by Strunk and White as an allegory for creating an image - Arentz's spare prose hearkens back to that practical guide).
I use Mark Nelson's Precision Digital Negative system to make the contact negatives needed for Palladium printing. I have settled on the Na2 method of contrast control. The paper I use for this process is Bergger COT 320 - expensive but beautiful, and great wet strength to make it through the clearing baths and archival wash.
I find myself going back to this book every few months, and leafing through the material. Something will make a bit more sense than it did when I started all this. A comment might clarify something I'd noticed.
The platinum and palladium process is not that difficult - and the results can be beautiful. Armed with this book, and Mark Nelson's method for creating digital negatives, the process can be simple and enjoyable!