Letter The author explains his long silence and missing of the Vienna symposium due to premature death of his closest colleague Gennady Zvenigorodsky, and hopes he will be able to participate in the IFIP celebrations Date: 10.12.1984 Original document language: English Authors: Andrei Petrovich Ershov Persons: Gennadi Anatolievich Zvenigorodsky Addressee: Heinz Zemanek