Unicode symbol map for PDFs

I'm checking new PDFs  from SRTR ADR for section 508 accessibility. My first check shows me that document has some problems with Unicode mapping. My editors don't know what to do. So, I searched Internet for the answers. Actually, I found very good site which is very helpful solving my problem.  I copied some mathematical symbols into my pdf files and it solves the problem with accessibility.  I'm not a first one, who has problem with mapping UNICODE symbols, so I offer you a real help. I hope, it will work for you.