Owing to the fact that a Living Reviews in Relativity article may evolve over time, we recommend to cite the article as follows:
Oscar A. Reula,
"Hyperbolic Methods for Einstein's Equations",
Living Rev. Relativity 1, (1998), 3. URL (cited on <date>):
http://www.livingreviews.org/lrr-1998-3
The date given as <date> then uniquely identifies the version of the article you are referring to.