@article{10_4064_ap81_3_2,
     author = {Dmitry Portnyagin},
     title = {A generalization of the maximum principle
 to nonlinear parabolic systems},
     journal = {Annales Polonici Mathematici},
     pages = {217--236},
     publisher = {mathdoc},
     volume = {81},
     number = {3},
     year = {2003},
     doi = {10.4064/ap81-3-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap81-3-2/}
}