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The procedure of having single digits called out, which the performer arranges in descending order to create a free page selection, thus subtly limiting the number of possible pages that can be selected, is included in Boardé's 1950 Mainly Mental, Volume Two, p. 95. An earlier source yet is likely. Another early description of this limiting force is found in H. G. Cleveland's “Dictionary Test” on p. 59 of The Linking Ring, Vol. 33 No. 8, October 1953.