I recently came across these math (and some physics) notes by Dexter Chua during his time as an undergraduate at Cambridge. Amazingly, he's transcribed several years of high quality math notes in LaTeX. Since members of this community frequently ask how improving their mathematical understanding, I thought to share this phenomenal resource. It looks like Dexter is now a PhD student at Harvard, and if you wish to reach out and show appreciation, his contact information is listed on the page.