Harpo Speaks! by Harpo Marx and Rowland Barber
Horse Feathers, starring the Marx Brothers (DVD cover)
Go West (1940) starring the Marx Brothers - Groucho, Chico, and Harpo
The Cocoanuts (1929), starring the Marx Brothers
Animal Crackers - The Marx Brothers - Groucho - Harpo - Chico - Zeppo - Margaret Dumont
A Night at the Opera, starring the Marx Brothers
A Day at the Races (1937) starring the Marx Brothers (Groucho, Chico, Harpo), Margaret Dumont, Allen Jenkins
Harpo Marx biography
The Marx Brothers - Chico, Zeppo, Groucho, Harpo