@article{MZ_1968__106_171005,
     author = {Siegfried Pr\"ossdorf},
     title = {Die {Indexformel} f\"ur ein {System} eindimensionaler singul\"arer {Integralgleichungen} nicht normalen {Typs.}},
     journal = {Mathematische Zeitschrift},
     pages = {73--80},
     publisher = {mathdoc},
     volume = {106},
     year = {1968},
     zbl = {0164.14301},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__106_171005/}
}