Other old papers, accessible on line

• Manifolds with pure non-negative curvature operator (with F. Mercuri and M. H. Noronha), 10 pages, Boletim da Sociedade Brasileira de Matemática, vol. 18 (1987), no. 2, pp. 13-22. DOI: 10.1007/BF02590020
• On compact spacelike submanifolds, 8 pages, Reports on Mathematical Physics, vol. 9 (1976), no. 1, pp. 107-114. DOI: 10.1016/0034-4877(76)90019-7
• On homogeneous conformally symmetric pseudo-Riemannian manifolds, 19 pages, Colloquium Mathematicum, vol. 40 (1978), no. 1, pp. 167-185.
• Conformally recurrent indefinite metrics on tori, 3 pages, Tensor, New Series, vol. 34 (1980), no. 3, pp. 260-262.