@article{MZ_1970__115_171340,
     author = {J\"urgen Witte},
     title = {\"Uber das {Verhalten} der {Spektralschar} eines elliptischen {Differentialoperators} in der {Umgebung} der {Singularit\"at} des {Potentials} q(x) = |x|... .},
     journal = {Mathematische Zeitschrift},
     pages = {140--152},
     publisher = {mathdoc},
     volume = {115},
     year = {1970},
     zbl = {0189.10902},
     url = {http://geodesic.mathdoc.fr/item/MZ_1970__115_171340/}
}