Comment on 'Characterization of InxGal_xAs/InP epilayers by X-ray double crystal rocking curve peak profile analysis

In a recent paper [1] the authors assert hat "we generalized Kato's statistical theory to the diffrac-tion of epitaxial layers....". The actually given the-ory was published five years ago [2, 3]. Indicated in [1] are the formulations, parameters and equations borrowed from [2, 3]; however, the authors [1] publish them as original results. Moreover, the statistical theory of a diffraction on multilayer sys-tems, including epitaxial ayers, heterostructures and superlattice is considered in detail in [4]. The authors of the paper [1] start from consid-eration of a general field of atom displacement u = (u) + 8u (1) and refer to work [5]. However such a representa-tion in paper [5] is not present. Also the statement that, in Ref. [5], a model of a mosaic crystal is considered is incorrect (such a model is considered in [6]). The expression (1) has for the first tim