@article{RRACEFN_1995_1995_1_a1,
     author = {D{\'\i}az, J. J.  and  Ramos, A. M.},
     title = {Positive and negative approximate controllability results for
semilinear parabolic equations.},
     journal = {Revista de la Real Academia de Ciencias Exactas, F{\'\i}sicas y Naturales },
     pages = {11-30},
     publisher = {mathdoc},
     volume = {89},
     number = {1-2},
     year = {1995},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RRACEFN_1995_1995_1_a1/}
}