ON MOBILITY OF SURFACE ELECTRONS IN LIQUID HELIUM AT TEMPERATURES UP TO 20 mK B.N. Eselson, A.S. Rybalko, Yu.Z. Kovdrya, A.A. Golub et S.S. Sokolov J. Phys. Colloques, 39 C6 (1978) C6-338 DOI: 10.1051/jphyscol:19786150