Dobbs, David E. “On the Maximal Number of Non-Overlapping Klein 4-Groups Inside an Elementary Abelian 2-Group”. Tamkang Journal of Mathematics 40, no. 2 (June 30, 2009): 113–116. Accessed April 29, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/460.