What to do about good references that cannot be located?

You can always hire a research agency or detective to help you track a person down. Using the web and networking are the most common ways to find old contacts but if you need a professional to located someone you may need to pay for the service. There are online resources you can use that are very affordable if you know the person's full name, last place of residence, social security or age. You can also track people down through their past schools or licensing agencies.