@article{MAN_1938__115_159964,
     author = {K. Friedrichs},
     title = {\"Uber die {Spektralzerlegung} eines {Integraloperators}},
     journal = {Mathematische Annalen},
     pages = {249--272},
     publisher = {mathdoc},
     volume = {115},
     year = {1938},
     zbl = {0018.07001},
     url = {http://geodesic.mathdoc.fr/item/MAN_1938__115_159964/}
}