@article{10_4064_ba61_3_7,
     author = {Adrian Kr\'olak},
     title = {A {Remark} on {Variational} {Principles} of
 {Choban,} {Kenderov} and {Revalski}},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {257--261},
     publisher = {mathdoc},
     volume = {61},
     number = {3},
     year = {2013},
     doi = {10.4064/ba61-3-7},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba61-3-7/}
}