@article{JRAM_1977__291_151859,
     author = {Mitsuru Nakai and Leo Sario},
     title = {On {Hadamard's} problem for higher dimensions.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {145--148},
     publisher = {mathdoc},
     volume = {291},
     year = {1977},
     zbl = {0345.31007},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1977__291_151859/}
}