One of the best ways to locate skilled potential candidates for whatever field in which you recruit is to target their user groups.
User groups are very neat organizations.
The bad news is you can be spammed to hell and back if you use them inappropriately. As you might be aware, the Internet allows recruiters to contact thousands of people with job offers. Unfortunately, the cookie-cutter aspect of this mass emailing results in instant deletion and negative reactions. Immediately, this moves you from a single usage resource to something that people will want to remember. And of course, you can use search engines too to locate your desired target niche.