I've gone back through a couple sources that I had read last year, and found them completely gone. One that's missing possibly just had the URL changed, but another is simply nonexistent.

Estimating the number of American children living in partner-violent families. Journal of Family Psychology, Vol. 20, No. 1, 2006.

http://smu.edu/experts/study-documents/family-violence-study-may2006.pdf

There might be a perfectly good explanation for this, but I don't see why a 7 year old study would stay up while an 8 year old one would be dropped.