Bodini, Olivier, Danièle Gardy, Bernhard Gittenberger, and Alice Jacquot. “Enumeration of Generalized $BCI$ Lambda-Terms”. The Electronic Journal of Combinatorics 20, no. 4 (December 17, 2013): #P30. Accessed April 18, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v20i4p30.