Forum:How do you get into vault 101 for the third time

how do i get into vault 101 for the third tome i need to get the medicen bobblehead :] —Preceding unsigned comment added by Stackattackjack (talk • contribs). Please sign your posts with ~ !

you don't. you should have gotten it when you had the chance. actually, you have 3 possible chances to get it: one when your about to take the G.O.A.T, one when your about to leave, and the last when you come back for the Trouble on the Homefront quest