Websites for professional associations closely tied to your field of interest can be great sources of information, but also keep in mind that at times such organizations may offer you membership-only content.
If you come across an association selling a book title where you’d like the Newhouse Librarian, Michael Pasqualoni, to do a rush order, contact him at mjpasqua@syr.edu (315) 443-3715 .
In PR, one has the Public Relations Society of America - http://www.prsa.org/ - which – for college students would mean membership in the student branch of PRSA known as Public Relations Student Society of America – which does maintain a Syracuse University Chapter
Keep in mind too that any subfield of PR you explore will have its own professional associations as well.