The correspondence includes letters from: Earl of Ancaster, Herman Baron, Jacques Barzun, Hans Maximilian Calmann, Pau Casals, Ronald B. Castle, Sir Kenneth Clark, John V. Cockshoot, Helmuth Domizlaff, Francis A. Drey, Vincent H. Duckles, Alfred Einstein, A.W.J. Fuller, Luigi Gonnelli, Wilhelm Hausenstein, Paul Hirsch, Robert von Hirsch, Cecil Hopkinson, Louis Kentner, Leonardo Lapiccirella, Stanley Pargellis, Percy A. Scholes, Mario Uzielli, Paul Wittgenstein and many antiquarian houses.