Fred Fox took over as the strip 's artist in the mid-1950s , followed by Roger Armstrong .
When Conselman died in the mid-1940s , his estate took over the strip and employed several writers , while Plumb received sole credit on the strip .
Fred Fox took over as the strip 's artist in the mid-1950s , followed by Roger Armstrong .
When Conselman died in the mid-1940s , his estate took over the strip and employed several writers , while Plumb received sole credit on the strip .