[1] Barnes B.: Groups of automorphisms and sets of equivalence classes of input for automata. J. ACM 12 (Oct. 1965), 561-565. MR 0183590 | Zbl 0199.04004

[2] Fleck A. C.: Isomorphism groups of automata. J. ACM 9 (Oct. 1962), 469-476. MR 0148515 | Zbl 0237.94019

[3] Hartmanis G., Stearns R. E.: Algebraic structure theory of sequential machines. Prentice-Hall, Englewood Cliffs, N. J. 1966. MR 0204224 | Zbl 0154.41701

[4] Weeg G. P.: The structure of an automaton and its operation-preserving transformation group. J. ACM 9 (July 1962), 345-349. MR 0153519 | Zbl 0137.25004