Former employers, professors or volunteer coordinators you've worked with are all great sources for short testimonials. (americasjobexchange.com)
Testimonials and / or references — ask current or former employers, colleagues, advisers or professors to write short testimonials about you or your work (lawyerist.com)
Further down the page there is a short testimonial and a brief overview of what Tableau software does. (blog.kissmetrics.com)