@article{MZ_1927__26_167931,
     author = {T Rad\'o},
     title = {Bemerkung \"uber das {DoppeIintegral} ?? (1+p2+q2) {\textonehalf}  dx dy},
     journal = {Mathematische Zeitschrift},
     pages = {408--416},
     year = {1927},
     volume = {26},
     url = {http://geodesic.mathdoc.fr/item/MZ_1927__26_167931/}
}