1. A. V. Aho, J.D. Ullman, The Theory of Parsing, Translation and Compiling, Volume I: Parsing, Prentice-Hall, 1972.
2. E. Allender, Invertible functions, Ph.D thesis, Georgia Institute of Technology, 1985.
3. C. Álvarez and B. Jenner, “Logarithmic space counting classes,” Proc. Structure Conference: 154–168, 1990.
4. J. Balcázar, J. Díaz and J. Gabarró, Structural Complexity I, Springer Verlag, New York, 1987.
5. A. Bertoni, D. Bruschi and M. Goldwurm, “Ranking and formal power series,” TCS
79: 25–35, 1991.