1. J. W. S. Cassels. An Introduction to Diophantine Approximation. Cambridge University Press, 1957.
2. A. Cobham. Uniform tag sequences. Math. Systems Theory 6 (1972), 164–192.
3. I. Glaister. Automaticity and closure properties. Master's thesis, University of Waterloo, April 1995.
4. G. H. Hardy and E. M. Wright. An Introduction to the Theory of Numbers. Oxford University Press, 1989.
5. J. E. Hopcroft and J. D. Ullman. Introduction to Automata Theory, Languages, and Computation. Addison-Wesley, 1979.