One of my favorite #mathematics papers is a paper by Milnor "On manifolds homeomorphic to the 7-sphere" from 1956.
https://www.scribd.com/document/75338163/John-Milnor-On-Manifolds-Homeomorphic-to-the-7-Sphere
It's only 7 pages long (8 with bibliography). Milnor showed that there exists a smooth 7-manifold homeomorphic but not diffeomorphic to the 7-sphere. The proof is absolutely beautiful and has influenced much of the development of high dimensional topology to this day.
@existential_wormhole thanks. I thought my link led to a free pdf too. at least I was able to download it at the time.
@herid said '1 upload for a download' for me or something like that.
@herid Thanks to you for sharing. Very Interesting!