Gaussian 03 Online Manual
In general, we recommend citing the original references describing the theoretical methods used when reporting results obtained from Gaussian calculations, as well as giving the citation for the program itself. These references are given in the discussions of the relevant keywords. The only exceptions occur with long established methods such as Hartree-Fock theory which have advanced to the state of common practice and are essentially self-citing at this point.
In some cases, Gaussian output will display the references relevant to the current calculation type.
Gaussian also includes the NBO program as link 607. If this program is used, it should be cited separately as:
NBO Version 3.1, E. D. Glendening, A. E. Reed, J. E. Carpenter, and F. Weinhold.
The original literature references for NBO can also be cited [12,13,14,15,16,17,18,19].