Molecular aspects of bioelectricity. Festschrift and proceedings of the International Symposium and Poster Session (Symposium on Molecular Aspects on Bioelectricity) in honour of David Nachmansohn on the occasion of his 81st birthday, Liege, May 25-27, 1980 under the auspices of the Univ. de Liege, Belgium and the Max-Planck-Inst. f. Biochemie, Martinsried/München