Discussion about the PDF this article is based on/links to:<p>2 years ago: <a href="https://news.ycombinator.com/item?id=21290881" rel="nofollow">https://news.ycombinator.com/item?id=21290881</a><p>7 years ago: <a href="https://news.ycombinator.com/item?id=8898299" rel="nofollow">https://news.ycombinator.com/item?id=8898299</a><p>7 years ago: <a href="https://news.ycombinator.com/item?id=8856226" rel="nofollow">https://news.ycombinator.com/item?id=8856226</a>