Szeto, G. (1980). ON GENERALIZED QUATERNION ALGEBRAS. International Journal of Mathematics and Mathematical Sciences, 1980(), 237-245. https://doi.org/10.1155/S0161171280000166
Fung, H. K. (1995). Some linear preserver problems in system theory [master's thesis, The University of Hong Kong]. Airiti Library. https://www.airitilibrary.com/Article/Detail?DocID=U0029-1812201200004895