@article{10_14708_cm_v52i1_5326,
     author = {Jurancy Ere\'u and Jos\'e Gim\'enez and Nelson Merentes},
     title = {On {Bi-dimensional} {Second} {Variation}},
     journal = {Commentationes Mathematicae},
     pages = { 39--59},
     publisher = {mathdoc},
     volume = {52},
     number = {1},
     year = {2012},
     doi = {10.14708/cm.v52i1.5326},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.14708/cm.v52i1.5326/}
}