@article{GDZPPN001171933, title = {New Error Bounds for the Penalty Method and Extrapolation.}, journal = {Numerische Mathematik}, volume = {22}, year = {1974}, pages = {153-166}, zbl = {0272.65092}, url = {http://dml.mathdoc.fr/item/GDZPPN001171933} }
King, J.T. New Error Bounds for the Penalty Method and Extrapolation.. Numerische Mathematik, Tome 22 (1974) pp. 153-166. http://gdmltest.u-ga.fr/item/GDZPPN001171933/