The Gromov Norm of the Product of Two Surfaces
  We make an estimation of the value of the Gromov norm of the Cartesian product of two surfaces. Our method uses a connection between these norms and the minimal size of triangulations of the products of two polygons. This allows us to prove that the Gromov norm of this product is between 32 and 52 when both factors have genus 2. The case of arbitrary genera is easy to deduce form this one. 
Lewis Bowen, Jesus A. de Loera, Mike Develin and Francisco Santos