Citing a text citation within a text citation?

Uh I'm not looking this one up. I recommend using the works cited or bibliography page of the work that used the other work to find the original information and use it to cite that example. It's not plagiarism; you just managed to procure the citation from another source. I don't see why you would then have to reference the second text for showing you the chunk of the other one. That's like citing a library's card catalog for telling you which book the right information is in.