@article{MAN_1980__247_163357,
     author = {Albrecht Pietsch},
     title = {Eigenvalues of {Integral} {Operators,} {I.}},
     journal = {Mathematische Annalen},
     pages = {169--178},
     publisher = {mathdoc},
     volume = {247},
     year = {1980},
     zbl = {0428.47028},
     url = {http://geodesic.mathdoc.fr/item/MAN_1980__247_163357/}
}