V.Lacquaniti,C.Battistoni,E.Paparazzo,M.Cocito,S.Palumbo: Tunneling barrer structure of Nb/Pb and Nb/Pb-In thin film Josephson junctions studied by Auger electron spectroscopy and x-ray photoelectron spectroscopy analysis Thin Solid Films, vol.94,n. 4, 1982, pp.331-339