Durrer, R. (2006) On the Frequency of Gravitational Waves.
http://theory.physics.unige.ch/~durrer/papers/freq.pdf

has been cited by the following article:

• TITLE: Analyzing If a Graviton Gas Acts Like a Cosmological Vacuum State and “Cosmological” Constant Parameter

  AUTHORS: Andrew Walcott Beckwith

  KEYWORDS: Graviton Gas, Cosmological Vacuum State

  JOURNAL NAME: Journal of High Energy Physics, Gravitation and Cosmology, Vol.3 No.2, April 30, 2017

  ABSTRACT: If a non-zero graviton mass exists, the question arises if a release of gravitons, possibly as a “Graviton gas” at the onset of inflation could be an initial vacuum state. Pros and cons to this idea are raised, in part based upon Bose gases. The analysis starts with Volovik’s condensed matter treatment of GR, and ends with consequences, which the author sees, if the supposition is true.