@article{10_4153_CJM_1993_028_6,
     author = {Ge, Zhong},
     title = {Collapsing {Riemannian} {Metrics} to {Carnot-Caratheodory} {Metrics} and {Laplacians} to {Sub-Laplacians}},
     journal = {Canadian journal of mathematics},
     pages = {537--553},
     year = {1993},
     volume = {45},
     number = {3},
     doi = {10.4153/CJM-1993-028-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1993-028-6/}
}