1. An Introduction to the Theory of Infinite Series;Bromwich,1965
2. On some double sequence spaces;Basarir;J. Indian Acad. Math.,1999
3. On the convergence of certain multiple series;Hardy;Proc. Cambridge Philos. Soc.,1917
4. On fuzzy metric spaces;Kaleva;Fuzzy Sets and Systems,1984
5. Extention of spaces c and c0 from single to double sequences;Moričz;Acta Math. Hungar.,1991