Signed "by Looey & Kurtzman", Looey is Lou Ferstadt,
this is the earliest signed work I've found by Harvey Kurtzman
This is the inside back cover of Four Favorites #8 (Dec. 1942).
I just purchased this at WonderCon in Oakland on Friday April 10, 2001, the day before I wrote the Kurtzman bio and had not ever looked through the comic until after I posted it.

To Kurtzman biography