For anyone interested, here's the e-book preview version of
Well-being: The Foundations of Hedonic Psychology. It's a fairly comprehensive book delving into this subject matter.
This is one of those academic sources where we've derived many of our mainstream conclusions from, such as that money (especially excess money) is a weak correlate to happiness.
I'm not going to lie. I didn't read this 600 page tome.
But the quick and dirty conclusion is that healthy relationships in marriage, friendship, and family are the strongest correlates to happiness.