Robert Caro on LBJ. Marcus Luttrell on war. Douglas Brinkley on Walter Cronkite. James Donovan on the Alamo. Steve Coll on ExxonMobil. Ben Fountain on a surreal Dallas Cowboys halftime show. Dan Rather and Sissy Spacek on themselves. For some reason, May has turned out to be a month like no other for Texas-related books. Here’s our handy guide.