Packing circles within ellipses. - Ernesto G. Birgin; Luis Henrique Bustamante; Hector Flores Callisaya; José Mario Martínez (Int. Trans. Oper. Res., 2013)

Quasi-integrability in deformed sine-Gordon models and infinite towers of conserved charges. - Harold Blas; Hector Flores Callisaya (Commun. Nonlinear Sci. Numer. Simul., 2018)