@article{DMDICO_2010_30_2_a6,
     author = {Prusi\'nska, Agnieszka and Tret'yakov, Alexey},
     title = {P-order necessary and sufficient conditions for optimality in singular calculus of variations},
     journal = {Discussiones Mathematicae. Differential Inclusions, Control and Optimization},
     pages = {269--279},
     year = {2010},
     volume = {30},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMDICO_2010_30_2_a6/}
}