Originally planned as a 6-volume series. In 2011, after publication of volume 4, the sponsor decided that he no longer wanted to continue with the financial support of the project. Volumes 5 and 6 were expected likely to be never published.
In 2014 a new sponsor was found and a 5th volume was published. A 6th volume was published in very limited numbers, not for sale, in 2017, with a 2nd edition, in commercial numbers, being planned for 2020. This may be followed by a 7th and final volume.