I started with Dick Arentz's "Platinum & Palladium printing" and Sullivan/Weese "the new platinum print" both are excellent books and between them you will have all the information you will ever need. I am partial to the Arentz's books since it teaches you how to calibrate your printing times, has a lot of info on papers and even if you decided to use (god forbid!
) digital negatives it has a chapter on it. It is a very complete book.
If you want to explore other processes, the book "Comming into focus" edited by John Barnier is also very informative. Each of the Chapter authors made a quick list of the materials and methods required for their chosen topic, so it gives the basic info needed to try any of the processes presented.
Good luck.