1. [1] Ash, C. J., and A. Nerode, "Intrinsically recursive relations", pp. 26–41 in Aspects of Effective Algebra (Clayton, 1979), edited by J. N. Crossley, Upside Down A Book Co., Yarra Glen, 1981.
2. [2] Coles, R. J., R. Downey, and B. Khoussainov, "On initial segments of computable linear orders", Order, vol. 14 (1997/98), pp. 107–24.
3. [3] Downey, R. G., B. Kastermans, and S. Lempp, "On computable self-embeddings of computable linear orderings", The Journal of Symbolic Logic, vol. 74 (2009), pp. 1352–66.
4. [4] Dushnik, B., and E. W. Miller, "Concerning similarity transformations of linearly ordered sets", Bulletin of the American Mathematical Society, vol. 46 (1940), pp. 322–26.
5. [5] Feiner, L., "Hierarchies of Boolean algebras", The Journal of Symbolic Logic, vol. 35 (1970), pp. 365–74.