For a description of SAPT see:
B. Jeziorski, R. Moszynski, and K. Szalewicz “Perturbation Theory
Approach to Intermolecular Potential Energy Surfaces of van der Waals
Complexes”, Chem. Rev. **94**, 1887-1930 (1994).
This review article contains references to the original papers
where the SAPT methods were developed.
The formulas used in the program are gathered in a
paper
by B. Jeziorski, R. Moszynski, A. Ratkiewicz, S. Rybak,
K. Szalewicz, and H.L. Williams
published in
*Methods and Techniques in Computational Chemistry: METECC-94*,
edited by E. Clementi, STEF, Cagliari, 1993, Vol. B, p. 79.

SAPT(DFT) method is described in: A. J. Misquitta, R. Podeszwa, B. Jeziorski, and K. Szalewicz,
“Intermolecular potentials based on symmetry-adapted perturbation
theory including dispersion energies from time-dependent
density functional calculations”, J. Chem. Phys., **123**, 214103 (2005).

A fairly extensive SAPT2016 User Guide is available in html and pdf forms.

Short installation instructions are also available.

The autoPES manual is avaiable here.