Seo, Seunghyun. “A Combinatorial Proof of Postnikov’s Identity and a Generalized Enumeration of Labeled Trees”. The Electronic Journal of Combinatorics 11, no. 2 (January 24, 2005): #N3. Accessed June 15, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v11i2n3.