BOUNDARY CONDITIONS FOR THE USADEL EQUATIONS AND PROPERTIES OF DIRTY S-N-S SANDWICHES Z.G. Ivanov, M.Yu. Kupriyanov, K.K. Likharev and O.V. Snigirev J. Phys. Colloques, 39 C6 (1978) C6-556-C6-557 DOI: 10.1051/jphyscol:19786250