1. Mavraganis, A.G., (1978). Astrophys. Space Sci., 54, 305–313.
2. Mavraganis, A.G., (1979). Astron. Astrophys., 80, 130–133.
3. Mavraganis, A.G., (1980). Astrophys. Space Sci., 70, 233–237.
4. Mavraganis, A.G. and Pangalos, C.A., (1983). Indian J. pure appl. Math., 14, 297–306.
5. Stornier, C.F., (1907). Arch. Sci. Phys. et Nat. Genève, 24, 350.