A look at the blog mentioned in the article proves you right:
<a href="http:&#x2F;&#x2F;awfullibrarybooks.net&#x2F;knapsack-problems&#x2F;" rel="nofollow">http:&#x2F;&#x2F;awfullibrarybooks.net&#x2F;knapsack-problems&#x2F;</a>
I don&#x27;t know the book, but it doesn&#x27;t seem outdated to me.