Some function of a complete finite measure space (for short, CFMS) into the duels and pre-duels of weakly compactly generated (for short, WCG) spaces are considered. We shall show that a universally weakly measurable function f of a CFMS into the dual of a WCG space has RS property and hounded weakly measurable functions of a CFMS into the pre-duels of WCG spaces are always Pettis integrable.