@article{EXMATH_2003_2003_1_a16,
     author = {Franco, Daniel and Nieto, Juan J. and O'Regan, Donal},
     title = {Soluciones superiores e inferiores para problemas de primer orden con condiciones de contorno no lineales.},
     journal = {Extracta mathematicae},
     pages = {153-160},
     year = {2003},
     volume = {18},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EXMATH_2003_2003_1_a16/}
}