https://www.gamesdatabase.org/Media/SYSTEM/Commodore_64//Manual/formated/Gunship_-_1986_-_MicroProse_Ltd..pdf
https://www.lemon64.com/games/details.php?ID=1123
http://www.gb64.com/game.php?id=3350&d=18&h=0
https://www.gamesdatabase.org/game/commodore-64/gunship
https://www.c64-wiki.com/wiki/Gunship#Reviews
https://en.wikipedia.org/wiki/Gunship_(video_game)
http://www.c64sets.com/details_db.html?id=7636&t=Gunship&i=manual%20page%2013
