If you are citing information from a source that is quoted or paraphrased from another source, note this in your in-text citation using qtd. in ("quoted in")
Although best practice is to track down the original source of the quotation, in some cases this may not be possible. Only include sources you have actually read in your works cited list; in the above example this would be Xue et al. (Huang's original work was not seen but is being cited indirectly).
MLA Handbook, 9th ed., pp. 284-85.