The Corellian Trilogy was created in 1995.
In the Star Wars mythos, there are two planets in the Corellian System named Talus and Tralus. They both orbit around the same barycenter, therefore they are "sister planets." There is a space station at the barycenter called Centerpoint Station, which played a major role in the Corellian Trilogy of books.
The Beaver Trilogy was created in 2001.
Gorse Trilogy was created in 1953.
Cairo Trilogy was created in 1956.
Larklight trilogy was created in 2006.
The Trilogy - album - was created in 2004.
U.S.A. trilogy was created in 1930.
Prehysteria trilogy was created in 1993.
Undersea Trilogy was created in 1992.
Viking Trilogy was created in 1957.
The Wimbledon Trilogy was created in 1993.
Auton trilogy was created in 1998.