  We introduce in the framework of the linear approximation of General
relativity a natural distinction between General gauge transformations
generated by any vector field and those Special ones for which this vector
field is a gradient. This allows to introduce geometrical objects that are not
invariant under General gauge transformations but they are under Special ones.
We develop then a formalism that strengthens the analogy of the formalisms of
the electromagnetic and the gravitational theories in a Special relativity
framework. We are thus able to define the energy-momentum tensor of the
gravitational field and to fully analyze the gravitational field of isolated
point masses or continuous distributions of them obtained by linear
superpositions.

General Relativity and Quantum Cosmology