@article{10_4153_CJM_2001_044_8,
     author = {Loewen, Philip D. and Wang, Xianfu},
     title = {A {Generalized} {Variational} {Principle}},
     journal = {Canadian journal of mathematics},
     pages = {1174--1193},
     year = {2001},
     volume = {53},
     number = {6},
     doi = {10.4153/CJM-2001-044-8},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-2001-044-8/}
}