Big thanks! I tried googling, though I didn't find the same book. Probably that's because current openstax University Physics is newer (published in 2016). Nevertheless, I am satisfied with the new version too
Recently I stumbled upon this topic - https://www.physicsforums.com/threads/simple-harmonic-motion-total-energy.736484/ and want to find out what textbook is in the photo. Any help would be greatly appreciated!