Boardgamegeek https://boardgamegeek.com/boardgame/34585/keltis
English - Keltis is a multi-player game based on Lost Cities, with some rules changes, later published with Knizia's original rules and theme as Lost Cities: The Board Game.
Ludovox http://ludovox.fr/jeu-de-societe/keltis-2491/
French - Nouvelle édition 2012. L'extension est incluse dans le jeu de base.