Ivica Martinjak and Mario-Osvin Pavcevic, BIBD-s for (13, 5, 5), (16, 6, 5) and (21, 6, 4) Possessing Possibly an Automorphism of Order 3. journal = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology. October 2009, vol. 34(10). 846 - 849 [viewed 19 September 2024]. Available from: https://publications.waset.org/pdf/8987.