Sorry I'm not sure what do you mean of relevant, so I will share some books related to conservative political philosophy which I like: George Will's Conservative Sensibility, Stephen Hick's Explaining Postmodernism, Robert Putnam's Bowling alone, Chantal Delsol's Icarus Fallen, Walter Williams' American Contempt for liberty, Harvey Mansfield's Manliness, Christopher Caldwell's The age of Entitlement, Murray Rothbard's Anatomy of The State, Jerry Muller(editor): Conservatism, Charles Murray's Coming Apart.