The expression and numerical results in the original letter were based on the use of Timoshenko–Mindlin plate theory and thus have an inherent frequency–plate‐thickness limitation when compared to results based on the use of elasticity theory. This limitation, which is noted by Young, was already noted, however, in the concluding section of the original letter. In addition it is noted that the second acoustic coincidence lobe was not attributed in the original letter to a dilatational mode, but was attributed to a flexural wave whose phase velocity at high frequencies approaches the velocity of a dilatational wave in an infinite elastic medium.Subject Classification: [43]30.50; [43]20.60; [43]40.24; [43]20.30.