Complex sentence: In fact, until the mid- 1990's there were almost no other books in print that even mentioned the Cube of Space and most of those that do now refer to Case's pioneering work on the subject.
Split into simpler sentences: In fact, until the mid- 1990's there were almost no other books in print that even mentioned the Cube of Space. The ones that do now refer and defer to Case's pioneering work on the subject.