In late 1976 Robertson predicted that the end of the world would come in 1982.
"Harold Camping, Ig Nobel Prize-winning mathematician, explains his mistake". improbable.com. Retrieved January 8, 2013; Restall, Matthew; Solari, Amara (2011). 2012 and the End of the World: The Western Roots of the Maya Apocalypse. Rowman & Littlefield. p. 121