Searching the name of this concept by Google, I found a piece of Web site news  about an experiment related to the concept. From this piece of news I noticed this: It was the original article  on this experiment published by Duncan Watts and colleagues at Columbia University in New York that was vaguely in my memory and made me write the blog mentioned above.
In the experiment by the researchers at Columbia University more than 60,000 people from 166 different countries took part. Participants were assigned one of 18 target people, and were asked to contact that person by sending email to people they already knew. The researchers found that in most cases it took between five and seven emails to contact the target. The result did not indicate that the email had made the world a more close-knit community, but confirmed the validity of Milgram's concept, which had emerged from a similar postal experiment .
- "All humans share a close relation" (2004).
- W. Knight, "Email experiment confirms six degrees of separation" NewScientist.com News Service (Aug. 7, 2003).
- P. S. Dodds, R. Muhamad, D. J. Watts, "An experimental study of search in global social networks" Science, Vol. 301, p. 827 (2003).