1. R. K. Sharma and P. V. S. Rao, Celest. Mech. 13, 137 (1976).
2. M. Khanna and K. B. Bhatnagar, Indian J. Pure Appl. Math. 29, 1011 (1998).
3. M. Khanna and K. B. Bhatnagar, Indian J. Pure Appl. Math. 30, 721 (1999).
4. J. Singh and J. J. Taura, Astrophys. Space Sci. 343, 95 (2013).
5. A. A. Ansari, Int. J. Appl. Appl. Math. 13, 818 (2018).