Summers has written about historical figures including Tsar Nicholas II of Russia, President John F. Kennedy, FBI Director J. Edgar Hoover, President Richard Nixon, and Admiral Husband Kimmel, who commanded the U.S. fleet at Pearl Harbor. He is author of a major book on the &lt;a href="September%2011%20attacks"&gt;9/11 attacks&lt;/a&gt; on New York and Washington. He also wrote biographies of celebrities Marilyn Monroe and Frank Sinatra, and investigations of Britain's Profumo Affair and the 2007 disappearance in Portugal of the little British girl, Madeline McCann.