1. A. Blass, C. Laflamme, Consistency results about filters and the number of inequiv-alent growth types. J. Symb. Log. 54, 54–56 (1989)
2. L. Fuchs, Infinite Abelian Groups, vol. II (Academic, Boston, MA, 1973)
3. R. Göbel, B. Wald, Wachtumstypen und schlanke Gruppen. Symp. Math. 23, 201–239 (1979)
4. R. Göbel, B. Wald, Martin’s axiom implies the existence of certain slender groups. Math. Z. 172, 107–121 (1980)
5. T. Jech, Set Theory (Academic, New York, London 1978)