How to do citations for comments on websites?

Which of these is most responsible for differences between the twentieth century to the twenty-first century?

Your business be in google top rank.more the rank more the business leads.for best seo and digital marketing services be confident to contact you can get best seo solutions by assistance experts provide digital marketing, website development, seo expert services and social media internet seo expert services your branding solutions. seo expert services ,best seo expert services,online seo expert services,

What is the original authority for copyright laws