@article{1183511690,
author = {Walsh, J. L.},
title = {The critical points of linear combinations
of harmonic functions},
journal = {Bull. Amer. Math. Soc.},
volume = {54},
number = {12},
year = {1948},
pages = { 196-205},
language = {en},
url = {http://dml.mathdoc.fr/item/1183511690}
}
Walsh, J. L. The critical points of linear combinations
of harmonic functions. Bull. Amer. Math. Soc., Tome 54 (1948) no. 12, pp. 196-205. http://gdmltest.u-ga.fr/item/1183511690/