The research you are requesting would be quite easy, simply find the section of the Constitution or the law that states that only those born of two U.S. citizen parents are “Natural Born Citizens.”
Not there. Unless you can persuade the Supreme Court to find it for you, perhaps under a penumbra of the emanations of Emmerich de Vattel or somewhere. And even if they so found, it would be in Congress's lap to do anything about it regarding Junior. Lots of luck with that!
It's almost certain, barring another amendment: Citizen at Birth == Natural Born Citizen.