If you want information about violence against nurses you might want to go to nurseadvocate.org . It has a lot of information and I used it when I had to do a presentation about violence against nurses

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As for unions, what state do you live in? I live in Canada where ALL nurses are unionized. Union information for us can be reached by going to rnabc.bc.ca and hitting the links button, but I have no idea where you would look for american info.