Caetano, Filipa. «On the existence of weak solutions to the Cauchy problem for a class of quasilinear hyperbolic equations with a source term». Revista Matemática Complutense, vol. 17, vol. 17, n.º 1, 2004, pp. 147-6, doi: https://doi.org/10.5209/rev_REMA.2004.v17.n1.16794.