Submatrices of summability matrices. Fridy, J.A. (1978) International Journal of Mathematics and Mathematical Sciences
Summability methods based on the Riemann zeta function. Chu, Larry K. (1988) International Journal of Mathematics and Mathematical Sciences
Summability of alternations of convergent series. Keagy, T.A. (1981) International Journal of Mathematics and Mathematical Sciences
Summierbarkeit der geometrischen Reihe auf vorgeschriebenen Mengen. Wolfgang, Trautner, Rolf Luh (1976) Manuscripta mathematica