'The US Congress: A Very Short Introduction' is the latest.
His other books are -
Electing FDR: The New Deal Campaign of 1932 (University Press of Kansas, 2007)
Our Constitution (Oxford University Press, 2006)
Reporting from Washington: The History of the Washington Press Corps (Oxford University Press, 2005)
Doing Oral History: A Practical Guide (Oxford University Press, 2003)
American Journalists: Getting the Story (Oxford University Press, 1997)
The Congress of the United States: A Student Companion (Oxford University Press,1993)
Press Gallery: Congress and the Washington Correspondents (Harvard University Press, 1991)
James M. Landis: Dean of the Regulators (Harvard University Press, 1980)
A book he has edited, The Oxford Handbook of Oral History, is due for publication in November 2010. He also also contributed many articles for handbooks related to American
He gave a very interesting interview to Verusca Calabria about oral history, which can be accessed here.
The Senate Historical Office "conducts oral history interviews with retired senior Senate staff and keeps extensive biographical and bibliographical information on former senators. A collection of more than thirty thousand Senate-related photographs and other illustrations is available for research and publication use. The Historical Office and its staff has also produced numerous publications through the years, covering all aspects of Senate history.". It's website can be accessed here.