  The construction of high order entropy stable collocation schemes on
quadrilateral and hexahedral elements has relied on the use of
Gauss-Legendre-Lobatto collocation points and their equivalence with
summation-by-parts (SBP) finite difference operators. In this work, we show how
to efficiently generalize the construction of semi-discretely entropy stable
schemes on tensor product elements to Gauss points and generalized SBP
operators. Numerical experiments suggest that the use of Gauss points
significantly improves accuracy on curved meshes.
