AN OPTICAL PUMPING SCHEME FOR EUV LASERS IN TWO COUPLED MEDIA USING A QUASI-CONTINUUM EMITTED BY RARE-EARTH ELEMENTS M. FINKENTHAL, J.L. SCHWOB et P. MANDELBAUM J. Phys. Colloques, 47 C6 (1986) C6-129-C6-133 DOI: 10.1051/jphyscol:1986617