Three books = 12 kyu?
I was browsing through the second edition of Janice Kim's third volume of Learn To Play Go(1998) and I came across this text box on page 103.
How To Improve
If you study Volumes I-III in this series, with a little experience your strength should be about ten to twelve kyu (in other words, you would receive about five handicap stones from the six kyu who played Black in the last chapter). If you have a lot of experience, you may be even stronger.
Far from it of me to question the wisdom of a woman who has been awarded dan rank by the Hankuk Kiwon; but it strikes me as a bit optimistic to say that 12 kyu can be achieved with three books. Even taking Ms. Kim's qualified definition into account (i.e. being able to take a five-stone handicap from a six kyu player), I don't think that many would agree to that as being a true measure of 12 kyu strength.
I've exchanged emails and chatted with several of you who have studied even more extensively and/or played many more games than I. My impression was that 12 kyu cannot be achieved with just three books and "a little experience". Some of us (yours truly included) even find that our ranks drop by at least four when playing on the Korean servers, DashN and CyberOro.
Of course, there's the possibility that Go world may also have changed dramatically since 1998.