American Experience: The Rockefellers: Ida Tarbell: Brief biography of US journalist Ida Tarbell (1857-1944) from the Web site of the PBS television series. Tarbell wrote a classic expose of Rockefeller and his Standard Oil Company.
Ida M. Tarbell: Brief account of an interview with Tarbell, which appeared in The Bookman magazine, January 1903. From the University of Virginia Library, Electronic Text Center Website.
Ida Tarbell Papers, 1896-1943: Finding aid for Tarbell's papers in the collections of Smith College, including biographical material, correspondence and writings.
New York Times: Obituary: Tarbell died at age 86 on January 16, 1944.
Wikipedia: Ida Tarbell: Brief encyclopedia article with hyperlinks to related topics.