I have come across a magazine that I "back issued" several years ago called Timeline, published by the Ohio Historical Society.
It had a nice article about Charlie Chan and Earl Derr Biggers with lots of photographs. It also has stills from Black Camel, CC Carries On and CC in Panama.
I just can't remember the price of the back issue!
For anyone who wants to contact them about whether there are still copiies available and at how much, you need to ask about the January/February, 1999 [Volume16/Number 1]. The title is Charlie Chan's Poppa: The Life of Earl Derr Biggers.
The address is:
Ohio Historical Society
1982 Velma Avenue
Columbus, Ohio 43211-2497
Thank you for this information. Today I emailed the Ohio Historical Society, and a gentleman named Tim responded and provided me with a toll-free telephone number where information regarding back issues may be found: (800) 840-6414. I plan to call sometime tomorrow.