The Vretha system was introduced in the 2009 reference book The Essential Atlas, authored by Daniel Wallace and Jason Fry, which placed it in grid square M-7. The name of the system built upon the mention of Vrethan stationery products in the 1993 book Monsters and Aliens from George Lucas, a publication that combines creature designs and photographs from various projects of George Lucas, creator of the Star Wars franchise, with original text by Bob Carrau. Lucasfilm employee Leland Chee, who maintains the Holocron continuity database, has indicated that information contained in Monsters and Aliens from George Lucas is non-canonical with respect to the Star Wars Legends continuity.
- The Essential Atlas