This explains "natural born Citizen" in Article II, Sec. 1, clause 5, US Constitution: How our first Presidents were "naturalized citizens" and had to be exempted from the "natural born citizen" (NBC) requirement; shows the common understanding of NBC at the time our Constitution was drafted and ratified; explains 14th Amendment citizenship; and shows why Marco Rubio and Ted Cruz are not NBCs.

http://oll.libertyfund.org/titles/2246#lfVattel_label_1642 [see Sections 212-217]

https://www.scribd.com/doc/33807636/A-Dissertation-on-Manner-of-Acquiring-Character-Privileges-of-Citizen-of-U-S-by-David-Ramsay-1789

https://www.scribd.com/doc/229039536/Canadian-Renunciation-Letter