@article{CC_2010_39_4_a6,
     author = {Chittaro, Francesca C. and Stefani, Gianna},
     title = {Singular extremals in multi-input time-optimal problems: a sufficient condition},
     journal = {Control and Cybernetics},
     pages = {1029--1068},
     publisher = {mathdoc},
     volume = {39},
     number = {4},
     year = {2010},
     zbl = {1287.49020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CC_2010_39_4_a6/}
}