William P. Sheridan was a famed NYPD detective in the late 19th century and early 20th century. He was known as the "man with the camera eye" because of his eidetic memory. In The Big Good-Bye, an Englishman named "Joyce" who had received a telegram had disguised himself so well that not even Sheridan would not have spotted him. (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 Sheridan was from page 164.