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Not without a lot of hacking. Neither Bootcamp, nor Parallels or VMWare allow it. There is a method out there that I read about that claims you can get Bootcamp to work on an external USB 3.0 drive, but it takes a ton of work and a lot of people in the comments can't get it to work like the OP despite following his directions.

So in short, not really. But if you're adventurous here is the link...

http://bleeptobleep.blogspot.fr/2013/02/mac-install-windows-7-or-8-on-external.html
 
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