What is the third Patrick Rothfuss book?

The third book by Patrick Rothfuss has the working title "Doors of Stone." As of June 2015, it is the unpublished final installment in the fantasy trilogy "The Kingkiller Chronicle."

The previous two books in "The Kingkiller Chronicle" – "The Name of the Wind" and "The Wise Man's Fear" – were published in 2007 and 2011. There is currently no release date for the third book in the series, though in a 2014 interview, Rothfuss stated that he was working on the novel. Since the release of "The Wise Man's Fear," he has also released several shorter works that take place in the same universe as the central "Kingkiller Chronicle" novels.