"The earliest unequivocal representation of the sixty-nine appears to be that on an oil-lamp preserved in the Munich Museum (Deutsches Museum), and first reproduced in Dr. Gaston Vorberg's ... portfolio, "Die Erotik der Antiken in Kleinkunst und Keramik" (Munich, 1921) plate 58, showing the woman lying on top of the man. Dr. Vorberg gives this ... to be of the period of the Roman Caesars ... . However, another oil-lamp of the same kind, showing the sixty-nine almost identically ... is more recently reproduced as a full-color plate, in Prof. Jean Marcadé's "Eros Kalos" (English-language edition, Geneva : Nagel, 1965), facing page 58, in ... lamps preserved in the Heracleion Museum in Greece."