@article{MTA_2016_1_2_a4,
     author = {Jean Saint Raymond},
     title = {A minimax theorem for linear operators},
     journal = {Minimax theory and its applications},
     year = {2016},
     volume = {1},
     number = {2},
     zbl = {1356.49007},
     url = {http://geodesic.mathdoc.fr/item/MTA_2016_1_2_a4/}
}