Thanks for the great question.
Brian is friends with many of the authors and and meets with them/shares interviews with them. This type of partnership helps the author get their books seen by a wider audience, as well as provides awesome content to our members. 📚
As far as copyrights go, Brian is also mindful of only providing a handful of big ideas and quotes from the books, and he clearly attribute them to the correct author. Just like in an essay in high school, you've got to cite your sources! 📖
I hope that you're able to relax (with a cup of tea + your favorite PhilosophersNote!) while knowing the content you're reading isn't pirated! ☠
Zak & the Optimize Team