1. M.Baronti and P. L.Papini, Norm-one projections onto subspaces of ? p , Ann. Mat. Pura Appl., to appear.
2. M.Baronti and P. L.Papini, Norm-one projections onto subspaces of?1 andc 0. Preprint.
3. J. Blatter andE. W. Cheney, Minimal projections on hyperplanes in sequences spaces. Ann. Mat. Pura Appl. (4)101, 215?277 (1974).
4. E. W.Cheney and K. H.Price, Minimal projections in ?Approximation Theory?. Edited by Talbot, New York-London, 261?289 (1970).
5. I. Hada, K. Hashimoto andS. Oharu, On the duality mapping of ??. Tokyo J. Math. (1)2, 71?97 (1979).