I really enjoy finding clues to a game's existence and the attached photos shows paperwork I found some time ago in a BattleZone manual packet. It may be common, but it's new to me.
I got a Pengo one time that had an unopened Sega flyer packet in the back door pouch with the Manual. Pristine flyers of Zektor, Tac Scan, Zaxxon, ect. I was stoked.