“…It is unclear, however, how the value of ρ was obtained in [10,11]. In particular, it is unclear why the dependence on the angle of incidence, θ 0 , in Figures 2 and 3 in [10] appears, because the spectral radius ρ depends only on the operator δG and may not depend on the angle of incidence, which enters only in the right-hand side of the IE (see equations (4), (6) and (1) in [10]). The parameter A, which describes attenuation of the wave and seems to be an essential parameter for analyzing the condition of absolute convergence (see discussion in [8]), does not appear in [10].…”