1. Blatter, Chr. and Specker, E., “Le nombre de structures finies d’une théorie à caractère fini,” Sciences Mathématiques, Fonds National de la Recherche Scientifique, Bruxelles 1981, 41–44.
2. Blatter, Chr. and Specker, E., “Modular periodicity of combinatorial sequences,” Abstracts Am. Math. Soc. 4 (1983), 313.
3. Blatter, Chr. and Specker, E., “Recurrence relations for the number of labeled structures on a finite set,” Logic and Machines, Lecture Notes in Computer Science, 171 (1984), 43–61.
4. Ehrenfeucht, A., “Application of games to some problem of mathematical logic,” Bull. Acad. Pol., Cl. III, 5 (1957), 35–37.
5. Evans, J. W., Harary, F. and Lynn, M. S., “On the computer enumeration of finite topologies,” Communications of the ACM 10 (1967), 295–297.