Signed l.r. in graphite; numbered 4/30 l.l.; monogrammed in the plate; On the back: Etiquette: The Lovers, December 1967, March 1968, 9 etchings, first estate, printed on Japanese vellum, each sheet. Each signed lower right in pencil: Marcel Duchamp, some numbered (edition of 30) lower left, Schwarz 646b Nauman 9.36. Exhibited: Marcel Duchamp: the Art of making art in the Age of mechanical reproduction, Achim Moeller Fine Art New York, 20 october 1999- 15 January 2000, cat. No. 124 Litterature: The complete works of Marcel Duchamp, par Arturo Schwarz editions Delano Greenidge 2000 New York ,pp.883-884, no. 652c.