a few researchers retrieved references cited to support claims but they evaluate them differently. Lexchin and Holbrook in a single country study retrieved and evaluated 114 references cited in 22 distinct advertisements and examine the methodological quality and relevance of references in pharmaceutical advertisements in Canadian Medical Association Journal (CMAJ).
Tense inconsistency- I would use the present or the past, but not both, to stop the jumping back and forwards.
financial source of the reference- this doesn't fit with 'supported' to me- I'd add a verb
low quality- the
are because there- are, because
Student or Learner