“Accidental Presidents” by Jared Cohen recounts the eight vice-presidents who succeeded to the presidency when the incumbent died in office. Three won re-election in their own right. Two were surprise successes who passed important reform measures. Two were so difficult that impeachment that the hosue considered impeachment. One was. “CSNY” by Peter Dogget tells about how four men briefly set the music world on its ear. In the wake of the Beatles, Crosby Stills and Nash stepped in with a brilliant debut that challenged the late Fabs with their songwriting, harmonies and lush arrangements. Adding neil Young to the mix, however, proved to be one star too many. “Duel” by Thomas Fleming recounts the famous rivalry between Hamilton and Burr. Their disagreements over the future of the country (Hamilton’s Federalism vs Burr’s populism) were made worse by personal animosity, which ended in a fatal duel. Our Man, a life of Richard Holbrooke recaps 50 years of American diplomacy through the life of a key player. Author George Packer (The Unwinding) does his usual excellent job.