Massengo Mophou, Gisèle y Jean-pierre Puel. «Boundary Sentinels with Given Sensitivity». Revista Matemática Complutense, vol. 22, vol. 22, n.º 1, 2009, pp. 165-8, doi: https://doi.org/10.5209/rev_REMA.2009.v22.n1.16342.