Entropy per nucleon (S/A) as a function of the nucleon density n at different temperatures, T = 20, 50, 70 MeV (from bottom to top) for SNM (left panel) and PNM (right panel). The continuous lines represent S/A calculated using Eq. (15) in which we employ the fit formula (Eq. (13)) for the free energy. The circular symbols represent the entropy per nucleon, calculated using Eq. (9) in the approximation of a mixture of two ideal Fermi gases of quasi-particles in the BHF mean fields.