@article{GDZPPN002178842,
title = {Singularities of Solutions to the Wave Equation in Three Dimensions.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {203},
year = {1960},
pages = {75-81},
zbl = {0099.07901},
url = {http://dml.mathdoc.fr/item/GDZPPN002178842}
}
Gilbert, R.P. Singularities of Solutions to the Wave Equation in Three Dimensions.. Journal für die reine und angewandte Mathematik, Tome 203 (1960) pp. 75-81. http://gdmltest.u-ga.fr/item/GDZPPN002178842/