Reference.

[mattsmom]

I would first ask if it's ok to use her as a reference for future clients and if she says yes, then ask if she would be comfortable if potential clients phoned her, or if she would like to just write a reference letter. I find that parents like to actually speak to the reference parent, rather then just read a letter.

I've never had a problem with giving potential clients the number of a past/present client. I usually use the same couple of parents anyway.