@article{2037, author = {Queir\'o, Jo\~ao Filipe}, title = {Generalized approximation numbers}, journal = {Portugaliae mathematica}, volume = {43}, year = {1985}, pages = {157-166}, zbl = {0601.15007}, mrnumber = {0875064}, language = {en}, url = {http://dml.mathdoc.fr/item/2037} }
Queiró, João Filipe. Generalized approximation numbers. Portugaliae mathematica, Tome 43 (1985) pp. 157-166. http://gdmltest.u-ga.fr/item/2037/