I saw a summary of The Sicilian, and it basically suggests that it's a side-story in the God Father novel. I haven't read The Sicilian yet, but I just want to know if it is indeed as side story.

The summary says that it happened when Michael Corleone was in excile, and his father Vito tasked hime to look for The Sicilian. Now, I was looking at the God Father novel for passages that at least suggest that Vito did asked Michael to look for this Sicilian.