Nickel was an element found in asteroids, including Oris and most likely Nickel One. It was also present on Antar 4, and Ruusan was said to have significant deposits of nickel.
- Galaxy Guide 4: Alien Races
- Galaxy Guide 4: Alien Races, Second Edition
- Goroth: Slave of the Empire
- Shadows of the Empire Planets Guide
- Star Wars: Empire at War: Prima Official Game Guide
- Star Wars: Empire at War: Forces of Corruption Expansion: Prima Official Game Guide
- The New Essential Guide to Alien Species
- Strongholds of Resistance