Citing this Article
 

Owing to the fact that a Living Reviews article may evolve over time, we recommend to cite the article as follows:

Jonathan Thornburg ,
"Event and Apparent Horizon Finders
for 3 + 1 Numerical Relativity",
Living Rev. Relativity 10,  (2007),  3. URL (cited on <date>):
http://www.livingreviews.org/lrr-2007-3

The date given as <date> then uniquely identifies the version of the article
you are referring to.