@article{10_4064_ap84_3_2,
     author = {Nguyen Van Chau},
     title = {Note on the {Jacobian} condition and the
 non-proper value set},
     journal = {Annales Polonici Mathematici},
     pages = {203--210},
     publisher = {mathdoc},
     volume = {84},
     number = {3},
     year = {2004},
     doi = {10.4064/ap84-3-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap84-3-2/}
}