@article{NUMA_1990__58_5_133521,
     author = {Lin Qun},
     title = {Fourth order eigenvalue approximation by extrapolation on domains with reentrant corners.},
     journal = {Numerische Mathematik},
     pages = {631--640},
     publisher = {mathdoc},
     volume = {58},
     number = {5},
     year = {1990},
     zbl = {0695.65064},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1990__58_5_133521/}
}