@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/