Whenever you can, use the original source for a quotation, rather than an "indirect source". If you can't access the original source, then create a full citation for your indirect source in the Works Cited list. Then, for the in-text or parenthetical citation, use this format: (qtd. in [last name of author of your indirect source] [page number of quotation]). This answer was adapted from p. 226 of the MLA Handbook, 7th ed.