@article{702365,
     title = {Local superconvergence analysis of the approximate boundary-flux calculation},
     booktitle = {Equadiff 7},
     series = {GDML\_Books},
     publisher = {BSB B.G. Teubner Verlagsgesellschaft},
     address = {Leipzig},
     year = {1990},
     pages = {275-278},
     zbl = {0737.73094},
     url = {http://dml.mathdoc.fr/item/702365}
}

Lazarov, R. D.; Pehlivanov, A. I. Local superconvergence analysis of the approximate boundary-flux calculation, dans Equadiff 7, GDML_Books,  (1990), pp. 275-278. http://gdmltest.u-ga.fr/item/702365/