Apocalypse by Harry Lorayne Volume 7, Number 2 February 1984 Page 884 et seq.
Personal Comment: As much as I love sandwich effects I don't like this one. The reason: The method is needlessly complicated. And I personally think that giving the spectator a choice doesn't matter in this case. But I know that this somehow seems to matter for some magicians. Me disagreeing with them should not stand in the way to showcase the effect here on my blog.