On the political left, professors Howard Zinn and James Loewen allege that United States history as presented in school textbooks has a conservative bias. "A People's History of the United States", by American historian and political scientist Zinn, seeks to present American history through the eyes of groups rarely heard in mainstream histories. Loewen spent two years at the Smithsonian Institution studying and comparing twelve American history textbooks widely used throughout the United States. His findings were published in "Lies My Teacher Told Me: Everything Your High School History Textbook Got Wrong".