"Policy and Law: Identifiability of de-identified data"
(includes, specifically, medial)
http://latanyasweeney.org/work/identifiability.html

EFF de-anon tool for browsers
Netflix/IMDB dataset
search query dataset

"how many bits" type of identification

https://en.wikipedia.org/wiki/Data_anonymization
https://en.wikipedia.org/wiki/De-anonymization