Owing to the fact that a Living Reviews in Relativity article may evolve over time, we recommend to cite the article as follows:
Jonathan R. Gair and Michele Vallisneri and Shane L. Larson and John G. Baker,
"Testing General Relativity with Low-Frequency, Space-Based Gravitational-Wave Detectors",
Living Rev. Relativity 16, (2013), 7. URL (accessed <date>):
The date given as <date> then uniquely identifies the version of the article you are referring to.