The Last Inmate (1973)
A Short Life (1978)
Ship of Gold (1982) (with Norman Polmar)
Fire & Innocence (1984)
Masquerade of Hearts (1987)
Black Bridge China (1988)
Murder in the Senate (1993) (with William S Cohen)

The Quest: A Report On Extraterrestrial Life (1965)
Vanishing Wildlife of North America (1974)
The World of the American Indian (1974)
We Americans (1975)
Rickover: Controversy and Genius - a Biography (1982) (with Norman Polmar)
Earth's Amazing Animals (1983)
Guardian of the Wild: The Story of the National Wildlife Federation 1936-1986 (1987)
War Games (1987)
Merchants of Treason (1988) (with Norman Polmar)
Treasures of the Tide (1990)
Walking to the Creek (1991)
World War II: The Encyclopedia of the War Years 1941-1945 (1991) (with Norman Polmar)
The Blue and the Gray (1992) (see Sam Abell)
Possessed (1993)
Climbing Kansas Mountains (1993) (with George Shannon)
Codename Downfall: Secret Plan to Invade Japan (1995) (with Norman Polmar)
Offerings At the Wall: Artifacts from the Vietnam Veterans Memorial (1995)
Spy Book: The Encyclopedia of Espionage (1996) (with Norman Polmar)
Shadows in the Sea: The Sharks, Skates and Rays (1996)
Animals of Africa (1997)
America from Space (1998)
Encyclopedia of Espionage (1998) (with Norman Polmar)
The Shark Almanac: A Fully Illustrated Natural History of Sharks, Skates and Rays (1999)
The Washington Monument: It Stands for All (2000)
Shark Attacks: Their Causes and Avoidance (2001)
Remember Pearl Harbor: American and Japanese Survivors Tell Their Stories (2001)
Why Truman Dropped the Atomic Bomb on Japan (2003) (with Norman Polmar)
George Washington, Spymaster: How the Americans Outspied the British and Won the Revolutionary War (2004)
The Bonus Army: An American Epic (2005) (with Paul Dickson)
Harriet Tubman, Secret Agent: How Daring Slaves and Free Blacks Spied for the Union During the Civil War (2006)
Remember Valley Forge: Patriots, Tories, and Spies Tell Their Stories (2007)