Jeff Kass's Columbine book's the best one out there imo. There's also "A teenage philosophy of awareness and existence" by Mathijs Koenraadt, focuses more on Harris and Klebold's worldviews in a more philosophical standard rather than the typical "This passage was indicative of *insert mental illness here*" line you get from most other books.
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Become a techno-barbarian today and get a free catgirl! You need to kill at least one jew to qualify. Alternatives include foxgirls and regular waifus. She will always be loyal, so treat her good.
Think with your noggin, not your n!ggin'.