Large group of 25 commemorative covers, each signed in ink by a Nobel Prize-winning scientist. Signers are: Sidney Altman, Hannes Alfeven, Felix Bloch, Melvin Calvin, Mario Capecchi, Edmond H. Fischer, Reinhard Genzel, Sheldon Glashow, Stefan Hell, Dudley R. Herschbach, H. Robert Horvitz, Brian Josephson, Jean-Marie Lehn, Anthony James Leggett, John C. Mather, Linus Pauling, Christiane Nusslein-Volhard, Jim Peebles, Arno Penzias, Richard R. Ernst, Richard R. Schrock, Andrew Schally, Thomas Sudhof, Harold E. Varmus, and Arieh Warshel. In overall fine condition.