Ma, Jun; de Grijs, Richard; Fan, Zhou; Rey, Soo-Chang; Wu, Zhen-Yu; Zhou, Xu; Wu, Jiang-Hua; Jiang, Zhao-Ji; Chen, Jian-Sheng; Lee, Kyungsook; Sohn, Sangmo Tony: RESEARCH PAPER: Old stellar population synthesis: new age and mass estimates for Mayall II = G1. In: Research in Astronomy and Astrophysics. 9. Jahrgang, Nr.6, Juni 2009, S.641–652, doi:10.1088/1674-4527/9/6/003, bibcode:2009RAA.....9..641M.
Ma, Jun; de Grijs, Richard; Fan, Zhou; Rey, Soo-Chang; Wu, Zhen-Yu; Zhou, Xu; Wu, Jiang-Hua; Jiang, Zhao-Ji; Chen, Jian-Sheng; Lee, Kyungsook; Sohn, Sangmo Tony: RESEARCH PAPER: Old stellar population synthesis: new age and mass estimates for Mayall II = G1. In: Research in Astronomy and Astrophysics. 9. Jahrgang, Nr.6, Juni 2009, S.641–652, doi:10.1088/1674-4527/9/6/003, bibcode:2009RAA.....9..641M.