@article{NUMA_1979__33_132641,
     author = {J. Pitk\"aranta},
     title = {Boundary {Subspaces} for the {Finite} {Element} {Method} {With} {Lagrange} {Multipliers.}},
     journal = {Numerische Mathematik},
     pages = {273--290},
     publisher = {mathdoc},
     volume = {33},
     year = {1979},
     zbl = {0422.65062},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1979__33_132641/}
}