@article{MZ_1921__9_167623,
     author = {T., Carleman},
     title = {Zur {Theorie} der linearen {Integralgleichungen}},
     journal = {Mathematische Zeitschrift},
     pages = {196--217},
     year = {1921},
     volume = {9},
     zbl = {48.1249.01},
     url = {http://geodesic.mathdoc.fr/item/MZ_1921__9_167623/}
}