  In this review article we consider three most important sources of the
gravitational field of the Early Universe: self-interacting scalar field,
chiral field and gauge field. The correspondence between all of them are
pointed out. More attention is payed to nonlinear scalar field source of
gravity. The progress in finding the exact solutions in inflationary universe
is reviewed. The basic idea of `fine turning of the potential' method is
discussed and computational background is presented in details. A set of new
exact solutions for standard inflationary model and conformally-flat
space-times are obtained. Special attention payed to relations between `fine
turning of the potential' and Barrow's approaches. As the example of a
synthesis of both methods new exact solution is obtained.
