Here is a list of what 15 conservatives scholars and public policy leaders thought were the most harmful books of the last century.
1. The Communist Manifesto by Karl Marx
2. Mein Kampf by Adolf Hitler
3. Quotations from Chairman Mao by Mao Zedong
4. The Kinsey Report by Alfred Kinsey
5. Democracy and Education by John Dewey
6. Das Kapital by Karl Marx
7. The Feminine Mystique by Betty Friedan
8. The Course of Positive Philosophy by Auguste Comte
9. Beyond Good and Evil by Freidrich Nietzsche
10. General Theory of Employment, Interest and Money by John Maynard Keynes
I had to read #1 in college and I have read parts of 4, 5, 7.
(Thanks to Christine Miller for the tip.)