  In this paper, we apply the generalized integration constants method in field
theory to quantize Maxwell and the Klein-Gordon free fields. The study is
performed in both position and momentum spaces, to obtain equal-time Dirac
brackets among the fields and their conjugate momenta. The idea is to obtain
the brackets near the initial instant using the Taylor polynomial expansion,
and then deduce directly their expressions at any later time. In the case of
the Maxwell field, the interdependence of the field components (constraints)
requires the use the Helmholtz theorem to separate the transversal and
longitudinal parts. Keywords : Singular systems, constraints, Dirac brackets,
CI method, Taylor expansion, KG field, Maxwell field, Fourier transform,
Helmholtz decomposition.
