There are several documents describing IFEFFIT, FEFFIT, and AUTOBK:
AUTOBK Document: on-line
FEFFIT Document: PDF
FEFF Document: Feff Wiki
For Athena, Artemis, Hephaestus, be sure to check out Bruce Ravel's HoraeTipOfTheWeek Page.
For more information on XAFS and information on using Ifeffit and Friends, see: XAFS.ORG
Citing IFeffit and Friends
If you use Ifeffit and would like to cite it in a paper, here's the best reference:
"IFEFFIT: interactive EXAFS analysis and FEFF fitting" M. Newville, J. Synchrotron Rad. 8, pp 322--324 (2001).
If you use Horae (Athena, Artemis, Hephaestus) and would like to cite these in a paper, the best reference is:
"ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT" , B. Ravel and M. Newville, J. Synchrotron Rad. 12, pp 537--541 (2005).
Bruce's preference is that, if you cite the Horae reference, you also cite the Ifeffit reference.
The reference for Atoms is:
"ATOMS: crystallography for the X-ray absorption spectroscopist", B. Ravel J. Synchrotron Rad. 8, pp. 314-316 (2001)