Owing to the fact that a Living Reviews in Relativity article may evolve over time, we recommend to cite the article as follows:
José Maria Martí and Ewald Müller,
"Numerical Hydrodynamics in Special Relativity",
Living Rev. Relativity 6, (2003), 7. URL (accessed <date>):
http://www.livingreviews.org/lrr-2003-7
The date given as <date> then uniquely identifies the version of the article you are referring to.