Thanks- I'm just following whatever extracts I find particularly interesting back to the original papers. (I found the bit about spare time leading to happiness particularly interesting, which is how I found the Aaker reference.)

One more thing: In the sentence "Aside from making them happier, you will also improve your relationship with them via the Benjamin Franklin effect, which — unintuitively — makes people like you more if you ask them for favors.", the link to the wikipedia article on the Ben Franklin Effect links to this:

http://en.wikipedia.org/wiki/Benjamin_Franklin_Effect

Instead of to the article here:

http://en.wikipedia.org/wiki/Ben_Franklin_effect