This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
One of them is in Narshe. To find him, you must first defeat Tritoch,
then move on from where it was.
The other is inside the Zone Eater. Don't know where to find the Zone
Eater? Finish Doma Castle, then talk to a man standing outside one of
the stores in Thamasa to find out where. If you ever find the Zone
Eater, let it Engulf your entire party. (Really.)