I personally think books are better because you retain so much more. Here's the marketing book I am reading right now for instance...I bought a marketing course from the same guy and it was no where near as helpful as the book: https://www.amazon.com/Startup-Growth-Book-Business-Marketing/dp/1953153526
New to Reddit, but my favorite business book at the moment is The Startup Growth Book. All about growing a business without spending tons of money on Marketing.
You should check out the Startup Growth Book. I didn't know much about marketing and this book taught me everything I needed to know for my marketing internship. https://www.amazon.com/Startup-Growth-Book-Business-Marketing/dp/1953153526