Sub HighlightMultiAuthorCitations()
' Paul Beverley - Version 09.06.17
' Finds and highlights all the multi-author citations in the text

myColour = wdYellow
minDate = 1900

Set rng = ActiveDocument.Content
With rng.Find
  .ClearFormatting
  .Replacement.ClearFormatting
  .Text = "\(*\)"
  .Wrap = wdFindStop
  .Replacement.Text = ""
  .Forward = True
  .MatchWildcards = True
  .Execute
End With

myCount = 0
Do While rng.Find.Found = True
  endNow = rng.End
  Set rng2 = rng.Duplicate
  numYrs = 0
  For Each wd In rng2.Words
    If Val(wd.Text) > minDate Then
      numYrs = numYrs + 1
    End If
  Next wd
  If numYrs > 0 Then
    txt = rng.Text
    numCommas = Len(txt) - Len(Replace(txt, ",", ""))
    If numCommas > numYrs Then rng.HighlightColorIndex = myColour
  End If
  rng.Start = endNow
  rng.End = endNow
  rng.Find.Execute
Loop
End Sub