@article{NUMA_1971__18_132100,
     author = {C.A. Hall and R.E. Carlson},
     title = {Ritz {Approximations} to {Two-Dimensional} {Boundary} {Value} {Problems.}},
     journal = {Numerische Mathematik},
     pages = {171--181},
     publisher = {mathdoc},
     volume = {18},
     year = {1971},
     zbl = {0213.17002},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1971__18_132100/}
}