May 6, 1952: The monster is sighted

This is the first strip in which Lucy does something actively antagonistic against another character (who is not her unseen father). It is also quite a clever little joke on pool ol' Charlie Brown.

April 8, 1952: Followed By Monomaniacal

I love the look on Lucy's face in the third panel. The glaring round eyes really work for that one.

It might just be the printing, or the scan, but the second panel looks like Schulz didn't completely encircle the eyes, they look more like the parenthesis eyes Lucy and Linus get later.