@article{700844,
     title = {\"Uber ein Konvergenzprinzip bei Spektralzerlegungen},
     booktitle = {General Topology and its Relations to Modern Analysis and Algebra},
     series = {GDML\_Books},
     publisher = {Academia Publishing House of the Czechoslovak Academy of Sciences},
     address = {Praha},
     year = {1967},
     pages = {229-234},
     zbl = {0162.45402},
     url = {http://dml.mathdoc.fr/item/700844}
}

Kuhnert, F. Über ein Konvergenzprinzip bei Spektralzerlegungen, dans General Topology and its Relations to Modern Analysis and Algebra, GDML_Books,  (1967), pp. 229-234. http://gdmltest.u-ga.fr/item/700844/