1. Berkson A., Polynomial subfields over perfect fields, Nordisk Mat. Tidskr., 1973, 21, 29–30
2. Bremner A., Morton P., Polynomial relations in characteristic p, Q. J. Math., 1978, 29(115), 335–347
3. Beals R.M., Wetherell J.L., Zieve M.E., Polynomials with a common composite, preprint available at http://arxiv.org/abs/0707.1552
4. Margulis G.A., Discrete subgroups of semisimple Lie groups, Ergebnisse der Mathematik und ihrer Grenzgebiete (3), vol. 17, Springer-Verlag, Berlin, 1991
5. Waterhouse W., Intersections of two cofinite subfields, Archiv der Mathematik, 2004, 82(4), 298–300