Owing to the fact that a Living Reviews in Relativity article may evolve over time, we recommend to cite the article as follows:
Alan D. Rendall,
"Local and Global Existence Theorems for the Einstein Equations",
Living Rev. Relativity 1, (1998), 4. URL (accessed <date>):
The date given as <date> then uniquely identifies the version of the article you are referring to.