I'm not sure where you can find more, but if you look at his wartime comics they are quite interesting. For example, he was highly against American isolationism during the late 30s/ early 40s. He was also highly against workforce segregation, both serious hot button issues at the time. While this may paint he picture of him being quite the progressive, he was highly racist against the Japanese, drawing many insulting and flat-out racists caricatures of them during the war years. His comic from Nov. 8th 1941 is quite telling as well.
sorry, apparently it was dec. 8th
Or what I said...
Ha! Ever see any of his WWII-era political cartoons? This book in on my wish list.
This cartoon seems appropriate.