Authors
J. Chimpanzo
Department of Exact Sciences, Higher Polytechnic Institute of Soyo, Angola
M.V. Otero-Espinar
Department of Statistics, Mathematical Analysis and Optimization, University of Santiago de Compostela, Spain
A. Borges
Department of Mathematics, University of Trás-os-Montes e Alto Douro, Portugal
P. Vasco
Department of Mathematics, University of Trás-os-Montes e Alto Douro, Portugal
Department of Mathematics, University of Trás-os-Montes e Alto Douro, Portugal