Blackburn, Simon (1994). "ordered n-tuple". The Oxford Dictionary of Philosophy. Oxford guidelines quick reference (3 ed.). Oxford: Oxford University Press (published 2016). p. 342. ISBN9780198735304. Retrieved 2017-06-30. ordered n-tuple[:] A generalization of the notion of an [...] ordered pair to sequences of n objects.
Matthews, P. H., ed. (January 2007). "N-tuple". The Concise Oxford Dictionary of Linguistics. Oxford University Press. ISBN9780199202720. Retrieved 1 May 2015.