As part of filing a patent application, you are obligated to cite any prior art you know to be relevant to your invention. Citing a patent doesn't mean you are referencing it specifically in the specification. Thus, I don't think you are going to find some pointer to some specific reference in the patent document's text outside of the cited patents section. As you noted, the patent examiner also does a prior art search and may cite that prior art they deem to be relevant.
To answer your questions specifically.
Is it common to just have a list of references without actually
referring to them in the document?
Yes, I believe so. I think it is considered safer to cite known patents that are even remotely relevant rather than not doing so.
If I can't necessarily find whether they used my work, what is the
correct way of describing this citation?
It's just a citation. Your patent might simply be in the same field as the patent citing it or using a similar technology in a different field.
Is it correct to say they "used" my work?
No it isn't correct. They are simply citing your patent as relevant. They may or may not describe that relevance in the specification and if they do it may just be to explain why their invention is different.
Just to be clear, I am not an attorney, simply someone with several patents.
