http://educacion.practicopedia.lainformacion.com/geografia-e-historia/como-era-la-sociedad-romana-15646
https://www.youtube.com/watch?v=4UUCGZPcYME
https://www.youtube.com/watch?v=ufEclRGXV6k
https://www.youtube.com/watch?v=XcomBZoDC38
https://www.youtube.com/watch?v=Fv-rXzUAD6s