Vince, Andrew. “An Extremal Graph Problem on a Grid and an Isoperimetric Problem for Polyominoes”. The Electronic Journal of Combinatorics 31, no. 2 (April 5, 2024): P2.5. Accessed March 27, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v31i2p5.