The essentially many-particle counterparts of the famous Debye-Planck model for the lattice thermal capacity of 3-dimensional (3D) polycrystalline, spatially non-homogeneous amorphous and low-dimensional (2D, 'quasi'-1D) solids are presented. They are denoted herein as the 3D, 2D and 'quasi'-1D versions of the 'refined', static and isotropic 'Generalized Skettrup Model' (GSM). The key features and brief history of the original Skettrup's model as well as those of the 3D GSM, semi-classical Bose-Einstein, quantum Planck and Tolman distribution functions are described in the third section of...