@article{SMJ2_2002_28_1_a1,
     author = {Marchini, Elsa},
     title = {Porosity and {Variational} {Principles}},
     journal = {Serdica Mathematical Journal},
     pages = {37--46},
     year = {2002},
     volume = {28},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SMJ2_2002_28_1_a1/}
}