This is perhaps a totally random comment, but it's a question I had myself. Before I sent out stuff I'd written I was worried about someone ripping me off. The question I asked people I knew who knew was what could I do to insure that I got credit for writing what I'D written. What they told me was honestly surprising. First, if you go to untoward lengths to protect yourself it can actually sour publishers toward your work. It makes their life more difficult in terms of getting the rights and they tend to feel upset by the distrustful attitude of the author, but there are things you can do. The easiest way to verify that your work is yours is to seal a copy of it in an envelope and then mail it to yourself registered mail. When it arrives do NOT open, but keep the sealed envelope for your records. If anyone ever tries to rip you off this is generaly enough proof to stand up in court, if you need to sue someone. It's really easy to do and anyone thinking of publishing should do it before they start shipping their stuff around. Good Luck!