Unless you know the title and/or author of the book you are looking for, research topics should be searched by Keyword to maximize the number of references to a topic. A keyword search for "Beatles" yields over 50 search results.
However, another way to search is to browse by Subject. This strategy is especially useful if you are having trouble narrowing your topic.
Books about topics pertaining to The Beatles themselves can be found in the ML section of the library. You may wish to examine other books that deal with rock music. These are also classified as ML.
Since The Beatles' influence was not confined to music, and since they became an international cultural phenomenon, you will find books in many sections of the library that are potentially useful for your research project.
Here, There and Everywhere: My Life Recording the Music of the Beatles by 
Postmodern Humanism in Contemporary Literature and Culture: Reconciling the Void by 
The Beatles' Abbey Road Medley: Extended Forms in Popular Music by 
Keeping Score: Music, Disciplinarity, Culture by 
How the Beatles Destroyed Rock 'N' Roll: An Alternative History of American Popular Music by 
Fire and Rain: The Beatles, Simon & Garfunkel, James Taylor, CSNY, and the Lost Story of 1970 by 
Blackbird: The Life and Times of Paul McCartney by 
Outliers: The Story of Success by 
America's Uncivil wars: The Sixties Era from Elvis to the Fall of Richard Nixon by 
