the Constellation of Leo and a Chinese period near Zuben-Al-Akrab which is in the Constellation of Libra. Earth, 1881, Maison Fournaise, Chatou, France where Laureline takes Valérian to recuperate after their ordeal. Notes Board 12, panel 2 of this album contains a cameo appearance by Edgar P. Jacobs' comic book heroes Blake and Mortimer – they can be seen to the right of the panel, reading newspapers, as Valérian enters the bar of the Athenæum Club. The very last panel of this album (board 46, panel 5), depicting Valérian and Laureline enjoying a meal, is a homage to the 1881 painting Luncheon of the Boating Party by Pierre-Auguste Renoir . Various concepts in this album have appeared in other, earlier works of science-fiction. The notion of parts of the Earth being lifted and set adrift between the stars has appeared in James Blish's City In Flight series written between 1957 and 1959. Other concepts – artificial worlds, the gradual breakdown of reality and the notion that the Valérian clones don't realise they are copies – crop up frequently in the writings of Philip K. Dick whose fiction regularly touches on the theme of “What is real?” and “What is human?” 1977 graphic novels Valérian and Laureline