Owing to the fact that a Living Reviews in Relativity article may evolve over time, we recommend to cite the article as follows:
Håkan Andréasson,
"The Einstein-Vlasov System/Kinetic Theory",
Living Rev. Relativity 14, (2011), 4. URL (accessed <date>):
http://www.livingreviews.org/lrr-2011-4
The date given as <date> then uniquely identifies the version of the article you are referring to.