@article{MZ_1970__116_171380,
     author = {John Steinig},
     title = {The {Changes} of {Sign} of {Fractional} {Integrals.}},
     journal = {Mathematische Zeitschrift},
     pages = {183--190},
     publisher = {mathdoc},
     volume = {116},
     year = {1970},
     zbl = {0188.18501},
     url = {http://geodesic.mathdoc.fr/item/MZ_1970__116_171380/}
}