Steam Community :: Guide :: A Detailed Guide For Crash Bandicoot 2: Cortex Strikes Back
Crash Bandicoot Gems walkthrough: All green, white, red, blue, purple, yellow coloured Gem locations, Key locations, Secret Levels and how to 100% each game | Eurogamer.net
Crash Bandicoot 2: Hangin' Out Crystal/Gem all boxes 100% walkthrough - YouTube