On the Goldbach conjecture and the consistency of general recursive arithemetic. H.A. Pogorzelski (1974) Journal für die reine und angewandte Mathematik
On the ranges of discrete exponentials. Caragiu, Florin, Caragiu, Mihai (2004) International Journal of Mathematics and Mathematical Sciences
Ordered ultraconnected rings Melvin Henriksen, Frank A. Smith (1990) Commentationes Mathematicae Universitatis Carolinae