  It is shown that under lowering density or temperature a nucleon Fermi
superfluid can undergo a phase transition to a new superfluid state
corresponding to superposition of states with singlet-triplet (ST) and
triplet-singlet (TS) pairing of nucleons (in spin and isospin spaces). Such
states arise as a result of branching from one-gap solution of the
self-consistent equations, describing ST pairing of nucleons. The density and
temperature dependence of the order parameters for new two-gap solutions is
determined in the model with Skyrme effective forces.
