Ihringer, Ferdinand. “Cross-Intersecting Erdős-Ko-Rado Sets in Finite Classical Polar Spaces”. The Electronic Journal of Combinatorics 22, no. 2 (June 15, 2015): #P2.49. Accessed April 21, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v22i2p49.