I have several of his that he issued as they came out, some are of those half-book size. Honestly I have to have close to all of his.
I recognize the "Prehistory" one in your link. Larson's Far Side is one of my all-time fav's!
Another one I recall, picture of two guys walking down the street approaching a corner, they cannot see around the corner but the readers can, guy says just about as they reach the corner "It's just one damn thing after another!" and two weird-ass alien-looking critters are coming from around the corner!
I got that one framed somewhere.