Owing to the fact that a Living Reviews
article may evolve over
time, we recommend to cite the article as follows:
Misao Sasaki and Hideyuki Tagoshi,
"Analytic Black Hole Perturbation Approach to Gravitational
Radiation",
Living Rev. Relativity 6, (2003), 6.
[Online article]: cited [<date>]
http://www.livingreviews.org/lrr-2003-6/
The date in 'cited [<date>]'
then uniquely identifies the version of the article you are
referring to.