The Search for Zei is the first half of the serial "The Hand of Zei", originally published in Astounding in 1950/1951. The second half was published as The Hand of Zei (Avalon, 1963). First combined by Ace as an Ace double using both titles, later recombined by Owlswick (1982) and subsequent publications as just "The Hand of Zei". Note that the Dutch edition of The Search for Zei is titled "De hand van Zei", switching the titles.