I have all my current families on my resume and a couple of my past clients too. I ask their permission of course and just list their full names and phone numbers. I think they have only received calls from a couple of people that I interviewed over the years. Not everybody calls your references. When families leave I ask for a letter of reference and some do it and some never get around to it but I have it with my interviewing portfolio. Also, you can ask your clients to put testimonials on your website.