Weird Thrillers #1-5 (Comic books, 1951-1952)
You can read them here.
Alpha and the Letter People (Comic books, Wayne Howard, 1977)
You can read these alternate takes on the Letter People here.
The Superhero Book: The Ultimate Encyclopedia of Comic-Book Icons and Hollywood Heroes (Book, Gina Misiroglu & David A. Roach, 2004)
You can digitally borrow it here.
Nancy: Listen, Laugh & Learn (Audio, 1982)
You can listen to the 1982 children's album, based on the newspapercomic strip, here.
The Comic-Stripped American (Book, Arthur Asa Berger, 1973)
You can borrow it digitally here.
It’s the Girl in the Red Truck, Charlie Brown (Video, 1988)
“I wanted this to be my ‘Citizen Kane,’ but it’s not.” - Charles M. Schulz. You can watch it here.
Here's an article, a podcast episode, and a 1988 review from the New York Times.
Some Comics by Gerard Ashworth (Comics, Gerard Ashworth, various years)
Some comics from the Australian independent cartoonist. You can read them here. Includes some issues of the Sick Puppy comics anthology, and Flayed Intentions, a guide to Australian comics of the early 90's.
Sport Billy Volumes 1, 3 & 4 (Videos, ~1980-1981)
Sci-fi fantasy sports cartoon based on a European comic. You can watch it here.
The Leather Nun and Other Incredibly Strange Comics (Paul Gravetti & Peter Stanbury, 2008)
You can borrow it digitally here.
The Essential Guide to World Comics (Book, Tim Pitcher & Brad Brooks, 2005)
You can digitally borrow it here.
Note: that isn't an off-model Nancy in the upper left - see the key diagram on one of the first few pages (viewable even without borrowing).