@article{GDZPPN002435632,
title = {Two-Parameter Maximal Functions in the Heisenberg Group.},
journal = {Mathematische Zeitschrift},
volume = {199},
year = {1988},
pages = {565-576},
zbl = {0638.42019},
url = {http://dml.mathdoc.fr/item/GDZPPN002435632}
}
Ricci, Fulvio; Sjögren, Peter. Two-Parameter Maximal Functions in the Heisenberg Group.. Mathematische Zeitschrift, Tome 199 (1988) pp. 565-576. http://gdmltest.u-ga.fr/item/GDZPPN002435632/