1. Ricovrimenti puntualmente numerabili di uno spazio numerabilmente compatto;Aquaro;Atti Acad. Naz. Lincei,1965
2. Z. Balogh, G. Gruenhage, Base multiplicity in compact and generalized compact spaces, Preprint
3. General Topology;Engelking,1989
4. A weakening of club …;Juhász;CMUC,1988
5. On minimal coverings of infinite sets;Klimó;Discrete Appl. Math.,1993