References for Self Employed

Other

I have just received a tenant application from back from a couple who I really get a good feeling about to rent my mum house. They are an older couple and only looking for short term as they have sold their own property and wanting to move abroad.
I want to complete the credit check and obtain references but the wife is self employed. Does this mean I can only obtain character references for her? Also, do I need anything from her accountant or will her personal details give me the sufficient information for a credit check?