Ian Pratt-Hartmann, Proceedings of the Joint Meeting of the Twenty-Third EACSL Annual Conference on Computer Science Logic (CSL) and the Twenty-Ninth Annual ACM/IEEE Symposium on Logic in Computer Science (LICS), CSL-LICS '14, Association for Computing Machinery, 14 luglio 2014, pp.1–10, DOI:10.1145/2603088.2603117, ISBN978-1-4503-2886-9.
Gary L. Peterson e John H. Reif, 20th Annual Symposium on Foundations of Computer Science (SFCS 1979), October 1979, pp.348–363, DOI:10.1109/SFCS.1979.25.