I'm a bit late to the party (as I see this thread is over two years old), but I didn't see among the sources for Asa Whitney the book, "The Whitneys: An Informal Portrait 1635-1975," by Edwin P. Hoyt. Weybright and Talley, New York.
It's not a genealogy; Hoyt has authored several biographies, and that's his approach here, where he features selected Whitneys. Asa is among them. I didn't find any Whitneys from my own line (which is Henry) so I didn't spend any time really evaluating it as a source. Others here may know something I don't; perhaps it's already been considered and discredited as a source. If not, it definitely lends some background and "color" to the vital statistics.