  The isothermal Tolman condition and the constancy of the Klein potentials
originally expressed for the sole gravitational interaction in a single fluid
are here generalized to the case of a three quantum fermion fluid duly taking
into account the strong, electromagnetic, weak and gravitational interactions.
The set of constitutive equations including the Einstein-Maxwell-Thomas-Fermi
equations as well as the ones corresponding to the strong interaction
description are here presented in the most general relativistic isothermal
case. This treatment represents an essential step to correctly formulate a
self-consistent relativistic field theoretical approach of neutron stars.
