Wings to Discovery: Shinryu in the Monster Arena drops them; you can also bribe malboros and great malboros, but don't ask me how much gil you need.
Winning Formula: receive 99 from monster trainer for unlocking all areas; Ultima Buster in the arena drops them; bribe Sand Worm.
Door to Tomorrow: Steal from Ultima Weapon; Bomb King in the arena drops them; receive 99 from the monster trainer when you unlock 6 areas
Here's where I found this-as far as I can recall it's accurate.