“…For reflection from edges and grooves see also [1186,1187,1606,1607,50,229,544,394], for picture displays see [597], for computer simulations see Sato [1321] and Harumi [617, 9, 618, 619, S 65]. Angles other than 90 0 are less interesting, but if the angle of incidence of a longitudinal wave (Fig.…”