@article{JRAM_1970__245_151060,
     author = {J.R. Edwards},
     title = {Characterizing wirkfelder of certain classes of summability methods.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {91--106},
     publisher = {mathdoc},
     volume = {245},
     year = {1970},
     zbl = {0208.37401},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1970__245_151060/}
}