@article{10_4064_am29_2_8,
     author = {Barbara Bily},
     title = {Optimal control for {2-D} nonlinear
  control systems},
     journal = {Applicationes Mathematicae},
     pages = {239--249},
     publisher = {mathdoc},
     volume = {29},
     number = {2},
     year = {2002},
     doi = {10.4064/am29-2-8},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/am29-2-8/}
}