Nonlinear Spinor Field in Bianchi type-I Universe filled with Perfect   Fluid: Exact Self-consistent Solutions
  Self-consistent solutions to nonlinear spinor field equations in General Relativity have been studied for the case of Bianchi type-I space-time filled with perfect fluid. The initial and the asymptotic behavior of the field functions and the metric one has been thoroughly studied. It should be emphasized the absence of initial singularity for some types of solutions and also the isotropic mode of space-time expansion in some special cases. 
B. Saha and G. N. Shikin