The six card repeat was invented by Tom Tucker. There are many presentations and methods of handling. Almost every classic, general magic text will have a version. Tarbell has several including the Senator Crandall routine. Hugard's Monthly published Elmer Applegit's fabulous 'one card pete' presentation, though I prefer the George Sand's handling. Bill Tarr's excellent Now You See It, Now You Don't' has a good impromptu gaffless version that is intimidating to those who have never tried it, but its the way most perform it now. And there is a super killer version hidden away in Ganson's Routined Manipulation series. A legendary magician did this for Mike Close and I in London and it stomped us. It's been sitting on my shelf for years!
I hope this establishes the value of having a well rounded working library. Two of these texts can be had at your local book store and each has hundreds of other tricks on which one could build a professional carreer.
Brad Henderson