Periodic Orbits for Billiards on an Equilateral Triangle. - Andrew M. Baxter; Ronald Umble (Am. Math. Mon., 2008)

Cup Products on Polyhedral Approximations of 3D Digital Images. - Rocío González-Díaz; Javier Lamar; Ronald Umble (IWCIA, 2011)

On the Z/2-Cohomology of 3D Polyhedral Approximations - Rocío González-Díaz; Javier Lamar; Ronald Umble (CoRR, 2012)

Computing Cup Products in Z2-Cohomology of 3D Polyhedral Complexes. - Rocío González-Díaz; Javier Lamar; Ronald Umble (Found. Comput. Math., 2014)