@article{MS2_1983__52_166843,
     author = {I. Ekeland},
     title = {Some lemmas about dynamical systems.},
     journal = {Mathematica Scandinavica},
     pages = {262--268},
     year = {1983},
     volume = {52},
     zbl = {0515.58026},
     url = {http://geodesic.mathdoc.fr/item/MS2_1983__52_166843/}
}