The internet archive page appears to be gone (which is scary ;), but I
found a URL pointing to the current page, which has all the same
stuff.
[4]: http://sites.stat.psu.edu/~ajw13/stat505/fa06/17_factor/07_factor_commun.html
[5]: http://sites.stat.psu.edu/~ajw13/stat505/fa06/17_factor/13_factor_varimax.html
[6]: http://psychweb.psy.umt.edu/denis/datadecision/factor/dd_fa_part_2_aug_2009.pdf
-[7]: http://web.archive.org/web/20051125011642/http://www.ncl.ac.uk/iss/statistics/docs/factoranalysis.html
+[7]: http://ncl.ac.uk/itservice/dataanalysis/advancedmodelling/factoranalysis/
"""
import itertools as _itertools