[@GRW], while the center-of-mass energy at which reference [@Wilson] has calculated the effects is slightly different from ours. In addition, one needs to match the event selection criteria more carefully for a full-fledged comparison. Finally, it should be borne in mind that in our analysis we have adopted a normalization of the string scale $M_s$, which, though widely used, is not necessarily uniform in the literature. However, in spite of such non-uniformities, Figures 3 and 4, together with Table 1, can perhaps be taken as faithful indications of the fact that the predictions on radiative Bhabha scattering are comparable to those on the photon-graviton channel, so far as the limits of the probe on the string scale in ADD models are concerned.

Pinning Down the Model
======================

A few comments are in order on how to distinguish graviton signals involving missing energy from similar ones arising from other kinds of new physics. For example, let us consider the well-known process $e^+ e^- \to \gamma G_n$, leading to a single-photon-plus-missing-energy signal. Such signals can be obtained in several other models. A model with an extra $Z'$ boson could lead to a process $e^+ e^- \to \gamma Z'$ with the $Z'$ decaying 