Here are the cites....http://harvardlawreview.org/2015/03/on-the-meaning-of-natural-born-citizen/
the Supreme Court's opinion in United States v. Wong Kim Ark:
It is universally admitted, both in the English courts and in those of our own country, that all persons born within the Colonies of North America, whilst subject to the Crown of Great Britain, are natural-born British subjects.
Nothing is better settled at the common law than the doctrine that the children, even of aliens, born in a country while the parents are resident there under the protection of the government and owing a temporary allegiance thereto, are subjects by birth.
The notion that there is any common law principle to naturalize the children born in foreign countries, of native-born American father and mother, father or mother, must be discarded. There is not, and never was, any such common law principle.
Persons who are born in a country are generally deemed citizens and subjects of that country." Supreme Court Justice Joseph Story, Conflict of Laws, § 48.