1. Fousianis, Ch.: 1966,Higher Algebra, Athens (Greek edition).
2. Mavraganis, A.: 1978,Astrophys. Space Sci. 54, 305.
3. Mavraganis, A.: 1978,Astrophys. Space Sci. 57, 3.
4. Sharma, R. K.: 1974, ?Perturbations of Lagrangian Points in the Restricted Three Body Problem?,Ind. J. Pure Appl. Math. 12, 124.