Domain Experts / Subject Matter Experts / Industry Experts have invaluable knowledge that you can (and should) apply during your UX process. Domain expert involvement is not an alternative to UX research, and a domain expert is certainly neither a “user expert” nor a designer.
Interviews
Domain Expert Interview — UX Knowledge Base Sketches
Knowledge
100 Tools to Launch & Grow Your Start-up Without Web Weveloper, Graphic Designer and (almost) Without Money