Proceedings of the Romanian Academy. Series A. Mathematics, Physics, Technical Sciences, Information Science (Proc. Rom. Acad. Ser. A Math. Phys. Tech. Sci. Inf. Sci.) (20160101), 17, no.~2, 117-125. ISSN: 1454-9069 (print).
Proceedings of the Romanian Academy. Series A. Mathematics, Physics, Technical Sciences, Information Science (Proc. Rom. Acad. Ser. A Math. Phys. Tech. Sci. Inf. Sci.) (20160101), 17, no.~1, 24-30. ISSN: 1454-9069 (print).