Koos existed as one of the jungle moon's four continents on Yavin 4. The scout Lile Gorsek provided the name for it.
- Galaxy Guide 2: Yavin and Bespin
- Galaxy Guide 2: Yavin and Bespin, Second Edition
- The Official Star Wars Fact File 15 YAV 1-4: Yavin 4
- Star Wars: Empire at War: Prima Official Game Guide (Indirect mention only)
- Star Wars: Empire at War: Forces of Corruption Expansion: Prima Official Game Guide (Indirect mention only)
- Strongholds of Resistance