Text note/comment instead of a reference

How can I insert a comment in among the references to journal articles and books in my bibliography?

So the bibliography would look like:

  1. J. Smith, “Title of article,” Journal name (2010)

  2. This is a random comment about something in the paper.  It is not an actual reference.  It is just some text I write.

  3. E. Ponym, “Title of article,” Journal name (2012)

  4. etc.

The inserted comment is cited from the text like the other references, i.e.:

This is some text in the body of the paper [2].  This is some more text [3].

Thanks,

from word, on the endnote ribbon, far left, the  “insert citation” dropdown, has a choice – insert note.  – it opens a box to type your text into and generates a numbered note in that position and in the bibliography.  

not sure where this is in the Mac version.