Former Defense Secretary Donald Rumsfeld talked about his new book. Known and Unknown, which he spent four years writing after leaving the George W. Bush administration. Mr. Rumsfeld has twice held the position of secretary of Defense, in the George W. Bush administration and the Gerald Ford administration. Other offices included chief of staff to Gerald Ford, United Nations Representative to NATO, and a member of Congress.In this interview, Mr. Rumsfeld talked about the process of writing the book. He also addressed some of the critical and positive reviews the book has received. Through viewing clips of an appearance on C-SPAN in 1991, Mr. Rumsfeld talked about his philosophy of presidential staff leadership. He also compared and contrasted his years in government with those in business.