@article{MM2_1990__67_1_155495,
     author = {Christian Berg and Bent Fuglede},
     title = {Liouville's operator for a disc in space.},
     journal = {Manuscripta mathematica},
     pages = {165--186},
     publisher = {mathdoc},
     volume = {67},
     number = {1},
     year = {1990},
     zbl = {0702.45015},
     url = {http://geodesic.mathdoc.fr/item/MM2_1990__67_1_155495/}
}