@article{1256049500, author = {Hennefeld, Julien}, title = {Compact extremal operators}, journal = {Illinois J. Math.}, volume = {21}, number = {4}, year = {1977}, pages = { 61-65}, language = {en}, url = {http://dml.mathdoc.fr/item/1256049500} }
Hennefeld, Julien. Compact extremal operators. Illinois J. Math., Tome 21 (1977) no. 4, pp. 61-65. http://gdmltest.u-ga.fr/item/1256049500/