0185-3309 0185-3309 S0185-33092021000400003 10.18781/r.mex.fit.2021-2 México 00 00 2021 00 00 2021 39 spe 59 62 1986 Edición de AM. Garibay 126 1992 630.972R62 630.972R62 135 1959 451