I have a Framework in place: {examples]

Book1 - Main Sheet
Book2 - Lists {for Data Validation]

Is there a simple way to use Data Validation when Book2 is closed?
I have searched this site & the WEB and have had no success.

I don't know yet why the source book2.xls has to remain closed..this is an
insurmountable challenge.....

Appreciate you time & suggestions

Terry