Bullying is the common denominator of harassment, discrimination, physical and sexual abuse, conflict and violence. There is a lot of overlap. Alternatively, find out about other relevant support groups in your area and refer people on. If you hold a stock of books remember that eventually some will go missing. It's probably better to hold a list of resources, then let people obtain their own copies.
Public libraries are excellent for books.
College, university or business libraries hold specialist publications and professional magazines, and are often open to the public for reference. I have a note of my Advice Line experience. Once you have established the group you will need a constitution. This simply states, in writing, the nature, objectives and constitution of the group and how you will handle issues like confidentiality. Although a group doesn't have to have a constitution, it will be stronger and more professional with one.