1. Conjugates in division rings;Herstein, I. N.;Proc. Amer. Math. Soc.,1956
2. American Mathematical Society Colloquium Publications, Vol. 37;Jacobson, Nathan,1956
3. A. R. Richardson, Equations over a division algebra, Messenger of Mathematics 57 (1927), 1-6.
4. H. Rohrbach, Review of paper [3], Jahrbuch über die Fortschritte der Mathematik 53 (1927), 122.