Yeung, Y. H. A. (1966). On the eigenvalues of square quaternion matrices [master's thesis, The University of Hong Kong]. Airiti Library. https://www.airitilibrary.com/Article/Detail?DocID=U0029-1812201200009512
Kadry, S., Kassem, H., Smaili, M., & Jaoude, A. A. (2010). Statistical Study of Complex Eigenvalues in Stochastic Systems. Research Journal of Applied Sciences, Engineering and Technology, 2(3), 233-238. https://www.airitilibrary.com/Article/Detail?DocID=20407467-201005-201009060083-201009060083-233-238