Probably super specific but worth a shot. Books about Classical Music

I would like book recommendations in the genre of biographies on classical Spanish composers/singers, and/or history of zarzuelas. I am studying classical singing and growing up there was one singer, Xiomara Alfaro, that to me is one of the best of the best. But I can't find a lot of information about her, let alone a book….

Any information is greatly appreciated and apologies if this is the wrong sub for this question/topic. If this is the wrong place, apologies and please let me know where to go! Thanks!