Billionaire Elon Musk is providing a summer reading list about one of his latest interests: heading off our extinction at the hands of future robot overlords. In a series of weekend tweets, the CEO of the SpaceX rocket company and the Tesla electric-car maker says humanity needs to be "super-careful" with artificial intelligence, which is "potentially more dangerous than nukes."

This isn't the first time Musk has raised the alarm about machines that could outthink us into subservience. In June, he told CNBC he worried that artificial intelligence could lead to "scary outcomes." But this time, he used his Twitter account to talk up a couple of books with detailed warnings: "Superintelligence" by Nick Bostrom and "Our Final Invention" by James Barrat — neither of which are exactly light reading. On the bright side, Musk also talked up "Guardians of the Galaxy" and "Mass Effect 2."

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Worth reading Superintelligence by Bostrom. We need to be super careful with AI. Potentially more dangerous than nukes. — Elon Musk (@elonmusk) August 3, 2014

While on the subject of AI risk, Our Final Invention by @jrbarrat is also worth reading — Elon Musk (@elonmusk) August 3, 2014

Hope we're not just the biological boot loader for digital superintelligence. Unfortunately, that is increasingly probable — Elon Musk (@elonmusk) August 3, 2014

— Alan Boyle, NBC News