Pulitzer Prize-winning historian Doris Kearns Goodwin has made a career out of studying American presidents. She's returning to her favorite subjects in a new book, "Leadership: In Turbulent Times." It focuses on Abraham Lincoln, Theodore Roosevelt, Franklin Delano Roosevelt, and Lyndon B. Johnson. It highlights their efforts to unite the country in tough times. Goodwin joins "CBS This Morning" to discuss her latest book.
