I think that these were distributed by the Nihon Kiin to various go clubs in order to popularize the game. They're out of print now (at least I assume so, though for all I know it may be possible to still get them via the Nihon Kiin); and there's no reason to try to get them now unless you're a collector. I've heard it claimed that the author of these is Aiko Okada, but the copies that I have just say that they're by the Nihon Kiin.
Last modified: Sun Aug 10 20:49:14 PDT 2003