The Origins of Wonder
The idea of concealing cards by secretly reversing them under the deck or a packet, then spreading off groups and displaying them, eventually turning them over and slipping them under the packet until all have apparently been shown, was first described by Martin Gardner in his trick “Vanish and Spell” from Cut the Cards, 1942, p. 14.
Nick Trost published “Seven Card Count” in The Linking Ring, Vol. 34 No. 12, Feb. 1955, p. 62, which is a handling variant in which a packet is false-counted by moving cards singly to the bottom of the packet and turning them over.
Ron Edwards, in “Edwardian Aces” from The Cardiste, No. 11, Aug. 1958, p. 12, applied the principle to retain a stock while seeming to have all the cards shuffled in groups by spectators. This strategy is sometimes called Edwards Holdout.