Owing to the fact that a Living Reviews in Relativity article may evolve over time, we recommend to cite the article as follows:
László B. Szabados,
"Quasi-Local Energy-Momentum and Angular Momentum in General Relativity",
Living Rev. Relativity 12, (2009), 4. URL (accessed <date>):
The date given as <date> then uniquely identifies the version of the article you are referring to.