There’s nothing in the ISO standard that requires you to give these references. Their processes that they’ve adopted to meet ISO accreditation may mandate it but that’s their issue not yours. However, if you don’t provide them, their processes may mean they can’t work with you.
Section 7.4 of the ISO 9001:2008 spec is related to Purchasing and reads (paraphrased):
7.4.1 Purchasing process – The org shall ensure purchased product conforms to specified purchase requirements. The type and extent of the control applied to the supplier is dependent upon the effect of the purchased product on the product realisation or the final product.
Essentially they need to define the criteria that they will evaluate/select their suppliers with based on the suppliers ability to supply the product in accordance with their requirements.
As you’re not ISO accredited they’re asking for references to prove you can deliver.
I’m a quality manager for a telecommunications company.