1. C. Lea,Le Vide Suppl. 201 (1980) 467.
2. J. Bernardini, C. Lea andE. D. Hondros,Scripta Metall. 15 (1981) 649.
3. S. Hardy andJ. Fine, in ?Materials Processing in the Reduced Gravity Environment of Space?, edited by G. E. Rindone (Elsevier, New York, 1982) p. 503.
4. H. Raether, in ?Excitation of Plasmons and Interband Transitions by Electrons?, Springer Tracts in Modern Physics, Vol. 88 (Springer, Heidelberg, 1980).
5. G. Meyer,Z. Phys. 148 (1957) 61.