Search-fu didn't find me a previous topic on this, so here we go.

Short version:

Pg 103, Table 3-17, Common Lore is Intelligence/Knowledge

Pg 117, Table 4-3, Common Lore is Intelligence/General

Pg 120, Common Lore paragraph, Common Lore is Intelligence/General

My thoughts:

Leave it at Intelligence/General as Common Lore should be common and cheaper to buy.