@article{IM_1991__104_1_143878,
     author = {David Spring},
     title = {On the regularity of solutions in {Convex} {Integration} theory.},
     journal = {Inventiones mathematicae},
     pages = {165--178},
     publisher = {mathdoc},
     volume = {104},
     number = {1},
     year = {1991},
     zbl = {0782.35014},
     url = {http://geodesic.mathdoc.fr/item/IM_1991__104_1_143878/}
}