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Using a top change style of action for switching a packet of cards dates back to the 19th century. Johann Hofzinser used the technique in “The Power of Faith,” detailed in Ottokar Fischer's Kartenkünste, 1910, p. 72 of the Sharpe translation. Fellow 19th century conjuror, Jean-Jacques-Maurice Talazac used the now-common end grip for the technique. His top change can be found in Camille Gaultier's La Prestidigitation Sans Appareils, 1914, p. 100.
There is a related technique that involves switching packets under the cover of drawing the face-up top card of the packet onto the deck. It was described by Arthur Hastings and David Bendix in “Close-up Top Change II” from Hugard's Magic Monthly, Vol. 14 No. 5., Oct. 1956, p. 481. Hastings and Bendix used a side-step, as in the Veeser Concept. Marlo refined the handling by changing the step to a break in “Packet Switches” from The New Tops, Vol. 5 No. 2, Feb. 1965, p. 24. In his second method he specially mentions the Le Temps Ace switch in Expert Card Technique, 1940, p. 249, which is actually a handling of the Talazac top change.