Louis de Broglie

Maurice de Broglie was his brother and occasional collaborator. Langevin was a colleague, Bose worked with him when he first came to Europe, and Le Lionnais and he jointly founded an Association of Writers on Science. Among his correspondents were Valéry (a personal friend) and Einstein (who had great respect for him). He threatened to sue Freymann for withholding publication of a book, but Freymann died and the book got published.