@article{SIGMA_2019_15_a80,
     author = {Janin J\"ager},
     title = {A {Note} on the {Derivatives} of {Isotropic} {Positive} {Definite} {Functions} on the {Hilbert} {Sphere}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2019},
     volume = {15},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2019_15_a80/}
}