Henry G. Gordon An Isomorphism of Complete Degrees of Finite-State Transformability [Citation Graph (0, 0)][DBLP] Information and Control, 1979, v:40, n:2, pp:192-204 [Journal]
Kai Hwang On the Periodicity of Regular Languages [Citation Graph (0, 0)][DBLP] Information and Control, 1979, v:40, n:2, pp:205-222 [Journal]