Thank you very much everyone for your help. But I see it's been a unfructuous search for the original DOS floppy images. :/
I've been unable to find it in eBay as well, and warez sites only host rips of the CD version.
I would ask support at the official website, but that would be surely a waste of time, and I'm pretty sure they would even ignore my mail.
I'll keep looking instead. Again, thank you for all your help.