I have the recording by Alfred Brendel and Simon Rattle whith the Wiener Philharmoniker (Philips) and I think it is superb. I to think that the 4th concerto is a great masterpiece. I study music history and last year I did some investigation on the Beethoven concertos, especially the piano concertos. I used mainly Leon Plantinga's book called the "Beethoven Piano Concertos". I had great difficulty finding good books specialized on this subject and would appreciate if somebody could give me some more references on books about the piano concertos. George Smith