On general features of warm dark matter with reduced relativistic gas W. S. Hipólito-Ricaldi, R. F. vom Marttens, J. C. Fabris, I. L. Shapiro and L. Casarini Eur. Phys. J. C, 78 5 (2018) 365 Published online: 09 May 2018 DOI: 10.1140/epjc/s10052-018-5840-y