Ambrose National was a bank in New York City.
In The Big Good-Bye, one of the females who called the master criminal Silent Forrester at the Plaza was a bank manager at the Ambrose. (TNG: "The Big Goodbye")
The pages seen in the episode were actually from the detective novel,
The Listening Man, by author John A. Moroso. This novel was published in 1924. Information on Ambrose National was from page 145.