" 

 :We've talked about this difference before, Lou.  Look at the sentence The Invention of Heterosexuality is sourced to: 

 ::Scholars in recent times have argued that notions of a homosexual and heterosexual identity, as they are currently known in the Western world, only began to emerge in Europe in the mid to late 19th century. 

 :See how it starts out, ""scholars in recent times have argued"", and then ends with a statement about what they have argued?  The source works for that sentence because it supports the claim that these arguments have been made in recent times.  To go back to NARTH for a minute, as I've said more times than I care to count, if you were to say, ""according to groups like NARTH and the American Family Association, gay men are more likely to be pedophiles"" would be a perfectly acceptable sentence, and NARTH would be a perfectly acceptable source.  If the article said, ""Notions of a homosexual and heterosexual identity...emerged in the late 19th century"" and then used the sources listed, that would be faulty, just like if you said, ""gay men are more likely to be pedophiles"" and used NARTH as a source it would be faulty.  - "