The Dutch artist Rien Poortvliet (1932-1995) is best know for "Gnomes" and many other illustrated books. But before he did those works on his own, he was a prolific book and advertising illustrator.
Rien Poortvliet museum and was allowed to take some pictures from Poortvliet's early illustrated books. You can survey his image collection here: http://web.me.com/heuerdesign/Gefunden/album_poortvliet_pim_frits_en_ida.html
Thanks, Christoph! http://www.christophheuer.com/
Rien Poortvliet on Wikipedia
Gnomes by Wil Huygen and Rien Poortvliet
Noah's Ark by Rien
Dogs by Rien