Tarmizi, R. A., and H. Sulaiman. “Characterisation of 5-Groups Having a X11-Covering With Core-Free Intersection: Pencirian Kumpulan-5 Yang Mempunyai Litupan-X11 Dengan Persilangan Bebas-Teras”. Journal of Science and Mathematics Letters, vol. 9, Feb. 2021, pp. 18-27, doi:10.37134/jsml.vol9.sp.3.2021.