This month's Juxtapoz magazine features an interview with Ed Emberley, one of my favorite children's book authors. The article shows one illustration created in his own natural illustrative style, which is distinct from the style of his 'how to draw' books.
The article also mentions an out-of-print book which Emberley considers his master work entitled "Suppose You Met a Witch". I remember seeing the book and found it used on Amazon, most of the copies are expensive but I found one in decent condition for about $15. Sample images from the witch book here and also on this other blog by Tom Karpe.
Here is a video and interview with Ed from the recent exhibition of his work:
http://vimeo.com/16097411
Amazon's Ed Emberley store
Emberley's site is http://edemberley.com