Akiyama, Kenzi, Masayuki Ogawa, and Chihiro Suetake. “On ${\rm STD}_6[18,3]$’s and ${\rm STD}_7[21,3]$’s Admitting a Semiregular Automorphism Group of Order 9”. The Electronic Journal of Combinatorics 16, no. 1 (December 8, 2009): R148. Accessed March 16, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v16i1r148.