“…It was observed by Quintanilla [7] that the Moore-Gibson-Thompson equation appears in the generalized thermoelastic theories based upon the introduction of the thermal displacement (see Green-Naghdi's model [8][9][10]) and using the Maxwell-Cattaneo constitutive equation for the heat flux vector. Besides, there is a recent, rich, and intense research activity of the third-order in time differential equations, either separately or coupled with the elastic deformations of medium, leading to valuable results concerning the well-posedness: Quintanilla [7], Pellicer and Quintanilla [11], Conti et al [12], Ostoja-Starzewski and Quintanilla [13], Bazarra et al [14], Fernandez and Quintanilla [15,16], and Fernandez et al [17]. All these studies suffer from an inconvenience, namely, that they prescribe initial and boundary data in terms of temperature (or thermal displacement), instead of including mixed data for temperature (or thermal displacement) and heat flux vector.…”