@article{GDZPPN002209233,
title = {Boundary behaviour of eigenfunctions of the Laplacian in a bi-tree.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {426},
year = {1992},
pages = {137-148},
zbl = {0734.31010},
url = {http://dml.mathdoc.fr/item/GDZPPN002209233}
}
Sjögren, Peter; Picardello, M.A. Boundary behaviour of eigenfunctions of the Laplacian in a bi-tree.. Journal für die reine und angewandte Mathematik, Tome 426 (1992) pp. 137-148. http://gdmltest.u-ga.fr/item/GDZPPN002209233/