Citation signals in numbered references I'm reformatting a manuscript from author-date referencing to Nature's (superscript) numbered referencing. How can I include citation signals such as 'e.g.,' or 'see'? For example, how should I reformat the following sentence?


  It was demonstrated that pigs can't fly (e.g., Smith, 1901).


I can omit the citation signal completely:


  It was demonstrated that pigs can't fly1.


but then important information about the non-exhaustiveness of the citation is lost.

Someone suggested this:


  It was demonstrated that pigs can't fly (e.g., 1).


But it looks somewhat strange. Any idea?
I dislike this citation style for just this reason.  

You can, however, get around it by turning the parenthetical citation into a phrase:


  A number of studies, including Smith1, have demonstrated that pigs can't fly.


More often, however, I see this being indicated implicitly by using more than one citation:


  A number of studies1-3 have demonstrated that pigs can't fly.