@article{PNA_2008_2008_1_a7,
     author = {Mesa, Vilma},
     title = {Solving {Problems} on {Functions:} {Role} of the {Graphic} {Calculator.}},
     journal = {PNA},
     pages = {109-135},
     publisher = {mathdoc},
     volume = {2},
     number = {3},
     year = {2008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PNA_2008_2008_1_a7/}
}