The first book is actually called “The World of Null-A”. I picked it up at a local used book store last year and enjoyed it. Haven’t read any more of the trilogy yet.
Even actuallier, the first book was titled "The World of Ā" but "to reduce printing costs, the 1953 and 1964 Ace Books paperback editions were entitled The World of Null-A, and the symbol Ā was replaced with "null-A" throughout the text." [1]
Ah, thanks for mentioning that. If you get the chance, the other two are pretty great as well. As an aside, one of my favorite authors, Neil Asher, recently blogged about A.E. van Vogt:
[1] https://en.wikipedia.org/wiki/The_World_of_Null-A#Publicatio...