@article{MZ_1964__83_170232,
     author = {S. Minakshisundaram},
     title = {Summability of {Eigenfunction} {Expansions.}},
     journal = {Mathematische Zeitschrift},
     pages = {321--335},
     year = {1964},
     volume = {83},
     zbl = {0122.30906},
     url = {http://geodesic.mathdoc.fr/item/MZ_1964__83_170232/}
}