Amtoft, Torben, Flemming Nielson, Hanne Riis Nielson, and Jürgen Ammann. “Polymorphic Subtyping for Effect Analysis: The Semantics”. DAIMI Report Series 25, no. 502 (April 1, 1996). Accessed February 4, 2026. https://tidsskrift.dk/daimipb/article/view/7031.