Reviewer asks to add more references to already many references For a submitted review paper, I got a response from one of the reviewers: &quot;More related references should be added&quot;. The thing is, I already have around 70 references, and as the topic is pretty specific, there are not many more references out there. I could probably find a few more after very time consuming search, but IMHO, the number of references is both sufficient and able to convey the point. Also the reviewer left literally only this one sentence on the issue and did not even make clear in which aspect the number of references are lacking.
I am still pretty fresh to the academic publishing world, and I don't really know how to answer this request. Can I simply decline the revision request? (the other two reviers did not critisize the number of references)
You could do the following -

Compare other papers in the journal and see how many references they
have put.
Extend references by multiple references for
one instance. Example: In deep learning there is a technique called
object detection. It has 3 top notch review papers for that field
(which I know of). Instead of citing one, I would cite all three in
this case. You could do the same in your case.
You could do what Prof Santa has mentioned in the comments.
Search for relevant references from your cited papers.
Cite the general stuff. Many a times, techniques used so widely, people don't cite them. You could cite them as well.

I think 70 is actually a lesser number cites for a review paper. They generally span between the range of 150-200 in the field I work in. Though I think it differs in every field.