We've looked at Dave Sim's notebook #9 six times already and last November's Cover Thumbnails. It covers issues Cerebus #80 through 86 and had 118 out of 200 pages scanned.
In the past we've seen some sketches of people that weren't directly Cerebus characters in the notebooks. For example, sketches of people he saw while on vacation, covered in Vacation Time: San Jose and Vacation Sketches Part Deux. We've also seen some other Sketches of People in a different notebook.
I found a couple more sketches in notebook #9:
|Notebook #9, page 47|
|Notebook #9, page 48|
|Notebook #9, page 49|