koko and the jumping block \n short cube a libre routine with a jack-in-the-box \n robert lotz
1945/27
tarbell course in magic — volume 4 Robert Lotz
mental blocks \n spectator and performer put different colored cubes in a tube, same order, both blindfolded \n james auer
1961
still more miracles in mentalism James Auer
Mental Blocks
spectator and performer put different colored cubes in a tube, same order, both blindfolded