Hypertext

In this video Alyssa P. Hacker explain how to use the Symbolics Hypertext Document Examiner:
­ https://www.youtube.com/watch?v=7DxYj32cvoE

And here Ted Nelson shows how hypertext should actually have been implemented:
­ https://www.youtube.com/watch?v=dNV3uWCfERU

Finally, a short videos about the history of linked knowledge:
­ https://www.youtube.com/watch?v=jFM8mv0wb8g