Cohomology algebra of the orbit space of free circle group actions on lens spaces

Suppose that G=S^1 acts freely on a finitistic space X whose mod p cohomology nring isomorphic to that of a lens space L^{2m-1}(p;q_1,...,q_m). In this paper, nwe determine the mod p cohomology ring of the orbit space X/G. If the ncharacteristic class alpha belongs H^2(X/G;Z_p) of the S^1-bundle S--> X..