Wan Mohd Fauzi, Wan Nor Farhana, et al. “The Central Subgroup of the Nonabelian Tensor Square of the Second Bieberbach Group With Dihedral Point Group”.
Journal of Science and Mathematics Letters, vol. 3, June 2015, pp. 40-49,
https://ejournal.upsi.edu.my/index.php/JSML/article/view/368.