@article{JOLT_2013_23_3_a2,
     author = {Richard Penney and Roman Urban},
     title = {Upper {Bound} for the {Heat} {Kernel} on {Higher-Rank} {NA} {Groups}},
     journal = {Journal of Lie Theory},
     pages = {655--668},
     year = {2013},
     volume = {23},
     number = {3},
     url = {http://geodesic.mathdoc.fr/item/JOLT_2013_23_3_a2/}
}