@article{MZ_1956__66_169631,
     author = {P.M. Petersen},
     title = {Almost {Convergence} and two {Matrix} {Limitation} {Methods.}},
     journal = {Mathematische Zeitschrift},
     pages = {225--227},
     publisher = {mathdoc},
     volume = {66},
     year = {1956},
     zbl = {0072.05503},
     url = {http://geodesic.mathdoc.fr/item/MZ_1956__66_169631/}
}