“…But there was only a limited number of papers trying to robustify the method, see e. g. [1,9,10,11,34,35,36,38,39,40,50,73] or [57] (and the references given there 5 ). Moreover, even these papers, including [66], consider the situation when the disturbances are homoscedastic, except of [7] where the idea of the generalized method of moments (GMM) is employed, see [26]. Due to the fact that GMM does not need to specify the underlying d. f., the method covers also the heteroscedasticity -in a latent way because GMM is in fact studied in the i. i. d. framework.…”