McNulty, George F. “Some Variations on a Theme of Irina Mel’nichuk Concerning the Avoidability of Patterns in Strings of Symbols”. The Electronic Journal of Combinatorics 25, no. 2 (May 11, 2018): #P2.22. Accessed May 26, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v25i2p22.