I doubt Yutopian will publish the other volumes of English version of Igo Hatsuyoron in the near future. Volume 1 was translated long ago and has been sold at a good discount by Yutopian for quite some time. It was originally translated from a 1988 Chinese edition of Igo Hatsuyoron which was the most up to date edition at the time.
Now there is a newer Chinese edition published in 2010. See my
blog entry for more details of the new edition.
Probably easier to look for the recently published Chinese edition than to wait for the continuation of the series.
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http://tchan001.wordpress.com A blog on Asian go books, go sightings, and interesting tidbits
Go is such a beautiful game.