Bluebook Format - how do you cite a case within a case?

Okay, so how do cite Case B, which is cited in case A and you need to attribute this source to case A? Do you write ...case B .... as cited in Case A, or is there a Bluebook answer to that that I haven't found yet?|||If you are citing case B, shouldn't you actually be looking at case B, rather than relying on case A to explain it (unless, of course, it is a lower court case and there is no record). Sorry I can't help further; my Bluebook seems to have disappeared from my office!