V. Durai Murugan, R. Seethalakshmi, and P. Namasivayam. “A Study on Complementedness in the Subgroup Lattices of $2\times 2$ Matrices Over $Z_{11}$”. International Journal of Mathematics And Its Applications, vol. 9, no. 1, Mar. 2021, pp. 63-65, http://ijmaa.in/index.php/ijmaa/article/view/102.