Prakasha, D.G., H.G. Nagaraja, and G. Somashekhara. 2014. “ON (N (k), ξ)-SEMI-RIEMANNIAN 3-MANIFOLDS”. Italian Journal of Pure and Applied Mathematics 32 (August):115-24. https://journals.uniurb.it/index.php/ijpam/article/view/6229.