My source is my common sense, something you've seemed to have checked at the door. Why would you believe, even for a moment, that Sarah Palin wrote any of those jokes? Do you need a "source" to tell you water is wet and fire is hot? Maybe you do.
If she couldn't write her own book, if she couldn't write her own convention speech, then why do you assume she wrote those jokes?
Perhaps Palin should be spending more time speaking about policy and less time imitating the celebrity de jour, the rest of the country might then start to take her as seriously as you apparently do. Until then, color me unimpressed.
So you can’t provide a source. I’d rather color you and your sock puppet a lovely clear shade of transparent.