Denoting references in final reference list with *

I have been asked for my dissertation to denote any excluded references (from my systematic review) with an asterisk (*)

However, when I put them in the next time I open the document they are gone. Is there a simple way to get around this?

You can never just edit an endnote inserted “field” and expect it to stay.  Where does this asterisk need to be?  Do you have them desiganted somehow in your library?  

It needs to be either before or after the reference. I’ve used numbered referencing but my tutor has specified that I need to denote my excluded references. If it’s not possible I’ll have to leave it

First assign a field name to one of the custom fields (name it “Excluded” for example by editing (in preferences) each of the the ref types that you need to mark as excluded – put your asterisk in the field of each record you want to mark. If you already have these records in a group, you can make this edit globally by using the copy/change/move tool.  

Edit your output style to contain that field either in the front of the Author or at the end after the final field.  

The bibliography template would then look something like the below for “journal” ref type (you could superscript the field if it looks better to you that way, and if you want a space before the author, make sure you add it before the | character and that you use a “link adjacent” character from the field dropdown.  

|Exclude|Author,| Title. |Journal, |Year|. Volume|(Issue)|: p. Pages|.