Grateful Dead historian Paul Grushkin (along with various folks from the ticket office) signs copies of his new book Dead Letters, a tribute to the extremely creative fan art with which Dead Heads hoped to win the favor of ticket office workers and score hard-to-get tix. At Barnes & Noble, Walnut Creek. As part of the Bookfair charity promotion, a portion of your purchase goes to the Rex Foundation. Details: http://rexfoundation.org/2011/09/22/dead-letters-event-for-rex-november…