1. Alissandrakis, C. E.: 1981, Astron. Astrophys. 100, 197.
2. Chen Zhen-cheng: 1961, Prikl. Mat. Mekh. 25, 150, 716.
3. Chen Zhen-cheng: 1981, Kexue Tongbaro 26, 16.
4. Chen Zhen-cheng: 1983, Proceedings of the Second Asian Congress of Fluid Mechanics, Science Press, Beijing, China, p. 550.
5. Chen Zhen-cheng, Weng Shi-da, and Xu Mei: 1981, Acta Astron. Sinica 22, 72.