Group 1
https://twitter.com/hashtag/OnThisDay?src=hash
https://twitter.com/RealTimeWW1
http://graus.nu/blog/yourhistory-entity-linking-for-a-personalized-timeline-of-historic-events/
http://www2.vcdh.virginia.edu/AHR/
Group 2
http://freedoms-ring.org/?view=Speech