  Two point correlation functions of the off-critical primary fields \phi_{1,
1+s} are considered in the perturbed minimal models M_{2, 2N+3} + \phi_{1,3}.
They are given as infinite series of form factor contributions. The form
factors of \phi_{1, 1+s} are conjectured from the known results for those of
\phi_{1,2} and \phi_{1,3}. The conjectured form factors are rewritten in the
form which is convenient for summing up. The final expression of the two point
functions is written as a determinant of an integral operator.
