  In this paper, we consider the linear theory for a model of a
thermopiezoelectric nonsimple material adopting the entropy production
inequality proposed by Green and Laws as presentated in Passarella (2022). We
establish reciprocity theorems and a variational principle for homogeneous and
anisotropic thermopiezoelectric nonsimple materials with a center of symmetry.
The proof of these theorems use the time convolution product and an alternative
formulation of the field equations. Moreover, a uniqueness result is
established without using the definiteness assumptions on internal energy.
