Online Books Page – University of Pennsylvania

Some context: This page mostly hosts links to freely available online resources (mostly PDFs from other University sites). The advantage is it will show useful results that mostly get lost in Google Search for a broad term (Eg: 'compiler').

I personally feel usability is fine but a little confusing compared to libgen. But that's not an apples-to-apples comparison. I personally don't prefer pirate technical works and search freely available ones (except those mandated by institution etc..).