Recomendado por un experto en el tema.
Repositorio de sistemas operativos antiguos en donde se recogen versiones “obsoletas” de DOS, Windows, Apple/Mac, OS2, Linux, BeOS, OS/400 entre otros
https://libgen.org/ is like a piratebay of comics and books. Download shared books and comics now!
Multibootusb, It is a very complete tool to make an USB device booteable with several Operative Systems and make it able to help you restoring damaged PC for example. Remember, from BIOS or in the first screen when PC starts, use the option boot from “USB Hard Disk or External Device” and when loads Multibootusb, just select the OS you prefer for installation or just live use. A very nice capability is that you can add or delete Operative Systems when you want from the tool Multibootusb after the first time. Now days, it downloadable from http://multibootusb.org/ (Maybe when you read this already changed)
Hope it was useful!