Gene M. Amdahl. Validity of the single processor approach to achieving large scale computing capabilities. In Proceedings of the April 18-20, 1967, spring joint computer conference, AFIPS ‘67 (Spring), pages 483–485, New York, NY, USA, 1967. ACM.
 Josh Barnes and Piet Hut. A hierarchical O(N log N) force-calculation algorithm. Nature, 324:446–449, December 1986.
 Rudolf Bayer and Edward M. McCreight. Organization and maintenance of large ordered indices. Acta Inf., 1:173–189, 1972.
 Noam Chomsky. Three models for the description of language. IRE Transactions on Information Theory, 2:113–124, 1956. http://www.chomsky.info/articles/195609--.pdf – last visited 14th January 2009.
 Martin Fowler. Refactoring: Improving ...