1. L. Aldeman: Time, space and randomness. Technical Report MIT/LCS/TM-131, Massachusetts Institute of Technology, 1979.
2. E. Allender: Invertible functions. Ph.D. dissertation, Georgia Institute of Technology, 1985.
3. I. Baker, J. Gill, R. Solovay: Relativization of the P=?NP question.SIAM J. Comput.,4, 1975, 431–442.
4. J. L. Balcázar: En torno a oraculos que ciertas maquinas consultan, y las espantables consecuencias a que ello da lugar. Ph.D. Dissertation, FIB, 1984.
5. J. L. Balcázar, J. Diaz, J. Gabarró:Structural Complexity, Vol. 1. Springer-Verlag, Berlin, 1988.