How do I properly cite the amount of times an article has been cited on Google Scholar? I wish to properly cite the amount of times a paper has been cited according to Google Scholar. However, I couldn't find a proper answer to this question. 

The paper in question is: 


  Blei, David M., Andrew Y. Ng, and Michael I. Jordan. "Latent dirichlet
  allocation." the Journal of machine Learning research 3 (2003):
  993-1022.


Hansen, S., McMahon, M., &amp; Prat, A. (2014) note that 


  LDA is widely used (...) and has been cited over 8,000 times


But they cite no source! What is the proper source to cite here?

My first thought was something like this: 


  LDA is widely used (...) and has been cited over 10,000 since its
  publication, a search on Google Scholar reveals (Google Scholar,
  date).


edit: I e-mailed my advisor and ended up citing Hansen et al. (2014) saying that the paper had already been cited 8000 times. Not really a satisfying answer ... alas ..
I don't find such citations to citation counts very helpful in reading an article. Assuming such numbers are reasonably accurate, they only represent a snapshot of the popularity of a technique at the time you wrote your article. I would recommend simply saying that it is a popular technique and leaving it at that.