Justin Daniel Kaplan was an American writer and editor. The general editor of Bartlett's Familiar Quotations, he was best known as a biographer, particularly of Samuel Clemens, Lincoln Steffens, and Walt Whitman. He won the National Book Award in Arts and Letters and the 1967 Pulitzer Prize for Biography or Autobiography for Mr. Clemens and Mark Twain.
Excerpt from Wikipedia, available under CC BY-SA 4.0.

Mr. Clemens and Mark Twain
1966
ISBN 9780671207076
When the Astors Owned New York
2008
ISBN 9781429515481
Mr. Clemens and Mark Twain A Biography
2003
ISBN 9780743251396