XPS Studies of Single Crystals of Bi-2212, Tl-2212 and Tl-2223 B.R. Sekhar, F. Studer, C. Martin, P. Srivastava et K.B. Garg J. Phys. IV France, 7 C2 (1997) C2-581-C2-582 DOI: 10.1051/jp4/1997104