Lots online
If you read Dr. Umland's site you won't need to buy a book. It's very complete, and a good place to start. Sorry, but there's no "cookbook" approach to CN, you'll be forced to learn a little bit about astronomy and the celestial space.http://home.t-online.de/home/h.umland/page2.htmAlso, the "CN Practice" website is just an excellent resource. I especially like the examples from Ed Falk since they use the sight reduction tables instead of a scientific calculator. I think it's pretty silly to say you're going to learn CN because electronic gizmos are unreliable, then rely on a calculator or laptop program to do your sight reductions

Pencil and paper, chart and protractor.http://www.celestialnavigation.net/practice.htmlIf you're going to buy stuff, buy these things...1. Nautical Almanac. There's one online, but it's incomplete, just buy one.2. A book of sight reduction tables, called "HO 229". There are several volumes, buy the one for the lattitude where you'll be practicing. Or the S-Table booklet (see below).3. A pad of chart worksheets. You can order them from West Marine.4. A protractor, or a divider and parallel rules. OR, instead of HO229, you might consider the "S-Table" method, which is much more concise (and mechanical). You can order the S-Table book from the Weems and Plath website, I think. I was just working out a sight of Arcturus with the S Table last night, seems to work great.Good luck, it can be a fun hobby. I think it's hard to teach yourself, but I did it. You would certainly get faster results if you took a course.Paulsv Escape Artisth336