Decoupling of the general scalar field mode and the solution space for   Bianchi type I and V cosmologies coupled to perfect fluid sources
  The scalar field degree of freedom in Einstein's plus Matter field equations is decoupled for Bianchi type I and V general cosmological models. The source, apart from the minimally coupled scalar field with arbitrary potential V(Phi), is provided by a perfect fluid obeying a general equation of state p =p(rho). The resulting ODE is, by an appropriate choice of final time gauge affiliated to the scalar field, reduced to 1st order, and then the system is completely integrated for arbitrary choices of the potential and the equation of state. 
T. Christodoulakis, Th. Grammenos, Ch. Helias, P.G. Kevrekidis, A.   Spanou