I’m new here so…good luck for me :-).
I’m using the numbered style of the references, now I need to use it but I need to add several references for
the same one number,for example:
 ref 1…
 ref 2…
 (a) ref 3a…(b) ref3b…(c) ref 4c… etc.
how do I do that?
Thank you in advance,