The sixth season of Game of Thrones will be most likely be adapted by David Benioff and D.B. Weiss from which George R.R. Martin book?
Game of Thrones (season 5):  The season primarily adapts material from "A Feast for Crows" and "A Dance with Dragons", the fourth and fifth novels in George R. R. Martin's "A Song of Ice and Fire" series, though it also uses elements from the third novel, "A Storm of Swords", as well as the upcoming sixth novel "The Winds of Winter". Game of Thrones (season 5):  The series is adapted for television by David Benioff and D. B. Weiss. The Winds of Winter: The Winds of Winter is the planned sixth novel in the epic fantasy series "A Song of Ice and Fire" by George R. R. Martin.
The Winds of Winter