1. Blass, A., Gurevich, Y.: Equivalence relations, invariants, and normal forms. SIAM J. Comput. 13(4), 682–689 (1984)
2. Dawar, A.: Feasible computation through model theory. Ph.D. thesis, University of Pennsylvania (1993)
3. Dawar, A.: Generalized quantifiers and logical reducibilities. J. Logic Comput. 5(2), 213–226 (1995)
4. Springer Monographs in Mathematics;H-D Ebbinghaus,1995
5. Fagin, R.: Generalized first-order spectra and polynomial-time recognizable sets. In: Karp, R.M. (ed.) Complexity of Computation, SIAM-AMS Proceedings, vol. 7, pp. 43–73 (1974)