In this paper we give a method for decomposing subclasses of different families of languages, into other possibly smaller families. This method can be used to produce languages not in a family by using known examples of languages not belonging to other families.
Stoc '75 Proceedings of Seventh Annual Acm Symposium on Theory of Computing, 1975, p. 121-125
7th Annual ACM Symposium on Theory of Computing. STOC 1975