HHGTTG 5 - Mostly Harmless
Adams, Douglas
HHGTTG 4 - So Long, And Thanks For All the Fish
HHGTTG 3 - Life, the Universe, and Everything
HHGTTG 2 - The Restaurant at the End of the Universe
HHGTTG 1 - Hitchhiker's Guide to the Galaxy
Dirk Gently 2 - The Long Dark Tea-Time of the Soul
Dirk Gently 1 - Dirk Gently's Holistic Detective Agency