Rafael Herrerías Pleguezuelo José García Pérez Salvador Cruz Rambaud A note on the reasonableness of PERT hypotheses. 60-62 2003 31 Oper. Res. Lett. 1 http://dx.doi.org/10.1016/S0167-6377(02)00151-7 db/journals/orl/orl31.html#PleguezueloPR03