I am referring to this situation: document B is alleged to infringe the copyright of document A.
Document B is hosted online (as I believe is necessary for the DMCA to apply).
Document A, the original work, is not online e.g. it is a printed book published in 1990.
By "DMCA takedown procedure" I mean the notice to the service provider, takedown, counter notice, safe harbor, etc.
The reason for this question is that many DMCA request forms (e.g. Google's) require a URL to the copyrighted work.
In the case of a paper book, can copyright holders just provide a citation of the publishing? Or do they need to scan a sample, post it online somewhere, and then provide a URL to it?
NB: assume the copyright was not registered.