Author: De Niro classics will shape his legacy

Brilliant, taciturn, droll, intimidating - Robert De Niro is regarded as one of the greatest American actors of all time and among the most private.

American author and film critic Shawn Levy spent four years trying to get a handle on the two-time Oscar winner while working on his biography entitled, Robert De Niro: A Life.

Levy says he learned a lot from De Niro's archive of scripts and production notes about the 71-year-old actor outside of his more than 80 movie roles.