In the English-speaking world, “Lorca has now surpassed Ibsen, Chekhov, and Brecht as ‘the most performed foreign-language playwright.’”The problem here is that I am quoting two sources. One if from 1993 (Johnston) the other from 2009 (Delgado). Here I am in 2014, citing a five-year old source who is in turn quoting a 21-year old source.
Now Lorca may still be the most performed foreign-language playwright. I simply don't know, though I suspect it is true. Delgado may know this independently of the citation from Johnston, or may be depending on Johnston's opinion. I haven't verified this independently, or figured out how Johnston reached that conclusion. Luckily for me, for my purposes it is enough to know that other people are claiming this and repeating the claim: I simply want to prove that Lorca is canonical outside of Spain, and especially in the Anglosphere, and has been such for a long time. If I am precise enough in my footnote here, I can distance myself from the truth-claim while using the quote for my argument.