A characterization of noncommutative quaternion rings

Carl W. Kohls
1974 Proceedings of the American Mathematical Society  
Noncommutative quaternion subrings of the ring of 4x4 matrices over a formally real field are characterized in terms of the form of commutators and the multiplicity of characteristic roots.
doi:10.1090/s0002-9939-1974-0349746-9 fatcat:cfvbmutzmnclvinngrbbe6cldq