@article{GDZPPN002213907,
title = {Characterization of best harmonic and superharmonic L1-approximations.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {475},
year = {1996},
pages = {1-16},
zbl = {0853.31002},
url = {http://dml.mathdoc.fr/item/GDZPPN002213907}
}
Armitage, D.H.; Gardiner, S.J.; Haussmann, W.; ... Characterization of best harmonic and superharmonic L1-approximations.. Journal für die reine und angewandte Mathematik, Tome 475 (1996) pp. 1-16. http://gdmltest.u-ga.fr/item/GDZPPN002213907/