The Six Bunny Wunnies Join An Encounter Group

Peanuts
Charles Schulz (April 8, 1971)
I always wanted a spin-off series that followed the adventures of The Six Bunny Wunnies.  Here's a list of all of their literary adventures mentioned over the years, along with the dates of the Peanuts comics when they were first mentioned (courtesy of Fandom).

• The Six Bunny Wunnies and Their Pony Cart (July 26, 1970)
• The Six Bunny Wunnies Go to Long Beach (April 8, 1971)
• The Six Bunny Wunnies Make Cookies (April 8, 1971)
• The Six Bunny Wunnies Join an Encounter Group (April 8, 1971)
• The Six Bunny Wunnies and Their XK-E (April 10, 1971)
• The Six Bunny Wunnies and Their Water Bed (April 12, 1971)
• The Six Bunny Wunnies and Their Layover in Anderson, Indiana (April 13, 1971)
• The Six Bunny Wunnies and the Female Veterinarian (February 10, 1972)
• The Six Bunny Wunnies Freak Out (October 23, 1972)
• The Six Bunny Wunnies Visit Plains, Georgia (September 26, 1977)