@article{MS2_1967__20_165990,
     author = {Mitsuru Nakai and Leo Sario},
     title = {Classification and {Deformation} of {Riemannian} {Spaces.}},
     journal = {Mathematica Scandinavica},
     pages = {193--208},
     publisher = {mathdoc},
     volume = {20},
     year = {1967},
     zbl = {0182.10601},
     url = {http://geodesic.mathdoc.fr/item/MS2_1967__20_165990/}
}