Pratt-Hartmann, Ian (2014년 7월 14일). 〈Logics with counting and equivalence〉. 《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. New York, NY, USA: Association for Computing Machinery. 1–10쪽. doi:10.1145/2603088.2603117. ISBN978-1-4503-2886-9.
Juris Hartmanis, Neil Immerman, Vivian Sewelson. Sparse Sets in NP-P: EXPTIME versus NEXPTIME. Information and Control, volume 65, issue 2/3, pp.158–181. 1985. At ACM Digital Library
Pratt-Hartmann, Ian (2014년 7월 14일). 〈Logics with counting and equivalence〉. 《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. New York, NY, USA: Association for Computing Machinery. 1–10쪽. doi:10.1145/2603088.2603117. ISBN978-1-4503-2886-9.