BILLSTEIN (Horst Erich). The Wonders of Sologne. Ten original watercolors by Hobi. Paris, Éditions André Vial, s.d. (1977), broadside (65 x 45 cm), 10 original watercolors, signed and uncaptioned, in leaves, matted on heavy paper and serpents, in printed folder, and in green cloth slipcase. Limited edition of 15 press-numbered slipcases (XII/XV). Nominative copy for Marie-Françoise Le Cocq, with an autograph dispatch from Hobi to the verso of the first cover of the folder, dated November 2, 1977, enriched with an Indian ink drawing (a boat aground among the reeds). ATTACHED: a certificate of authenticity signed by the artist (one in-8 sheet typewritten: "I, the undersigned Hobi ... certify that all the watercolors in this work have been executed by my hand, all different, without any graphic, mechanical or photographic process").