Owing to the fact that a Living Reviews in Relativity article may evolve over time, we recommend to cite the article as follows:
José A. Font,
"Numerical Hydrodynamics and Magnetohydrodynamics in General Relativity",
Living Rev. Relativity 11, (2008), 7. URL (accessed <date>):
The date given as <date> then uniquely identifies the version of the article you are referring to.