Frank goes by the identity of "Pete Castiglione." Castiglione is actually Frank's original last name in the comics before he legally changed it to Castle.
When Frank is seen lying on his bed reading 'The Crack-Up' by F. Scott Fitzgerald, the camera shortly afterwards zooms in on the alarm clock - showing it's 03:00 AM. This is, besides the title of the episode, also a visual quote of the books "...in a real dark night of the soul it is always three o'clock in the morning, day after day".
At the end of the episode Micro says, "Welcome back, Frank". It was a nod to the Garth Ennis/Steve Dillon comic book story line titled "Welcome Back Frank" from the 2000-2001 limited series that was published under the Marvel Knights imprint.
The Gnucci's that are referenced throughout the episode are a callback to the Gnucci Crime Family who had a big part in the Welcome Back Frank storyline.
Frank is reading "The Crack-Up" by F. Scott Fitzgerald, a compilation of articles that the iconic author wrote between 1931 and 1937. The title essay relates to the haplessness of life and the author's own crack or loss of hope.