“…This is quite usual when one wishes to particularly investigate the role of extra material rather than geometrical terms in gravity. Anyhow, f (R, T ) models with correction terms on both sides of Einstein's field equations can be seen in [56,70,75,78] and also [91,92,93]. Furthermore, for an f (R, T ) model containing a strong coupling between geometry and matter, such as f (R, T ) = R + αRT , with constant α, check [94].…”