I posted about Gustaf Tenggren previously but I wanted to mention him again... because, well, I just love his work. The Animation Archive (ASIFA) has couple more pages I wanted to point out - in particular is an article (with lots of images) about Tenggren's Little Golden Book style. When Tenggren left Disney he worked at making a name for himself. He also couldn't get fairly paid for a week's worth of work for a single illustration. He developed a beautiful simple style, reminiscent of illustrations from his Swedish roots. It became a Golden Book standard and influenced children's books ever afterward. Compare them to more elaborate illustrations.
•Tenggren's Little Golden Book style (ASIFA)
•Tenggren's Grimm's Fairy Tales (ASIFA)