Here are some suggestions:
Fiction: Any of Anthony Price's novels (roughly, about a security service that does research). Hilary Mantel's A Place of Greater Safety (French revolution). Marguerite Yourcennar, Memoirs of Hadrian.
Non-fiction: Henry Kissinger's Diplomacy. John Keegan, A History of Warfare. Simon Blackburn, Lust. A recently acquisition: Donald De Carle, Practical Watch Repairing.
Best wishes,
Bob