Longyear, Barry B. "Collector's Item"
Summary: A man finds a silver 1978 quarter and essays by his father's students about visits by a mysterious friend urging them to higher goals.
Published: In Analog Apr. 27, 1981; and It Came from Schenectady, Warner 1986 (0445202335).
Original in: English.
Translation: German by Joachim Koerber as "Sammlerstueck", in Analog 2 (ed. Hans Joachim Alpers), Mö 1982 (3811835599).