@article{10_4064_cm_67_2_197_216,
     author = {Pascal Auscher and A. ter Elst and Derek Robinson},
     title = {On positive {Rockland} operators},
     journal = {Colloquium Mathematicum},
     pages = {197--216},
     publisher = {mathdoc},
     volume = {67},
     number = {2},
     year = {1994},
     doi = {10.4064/cm-67-2-197-216},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-67-2-197-216/}
}