No matter your field of study, you are expected to properly cite all sources you use for your academic research. It is considered good form to credit the authors or originators of ideas you are using to build your own arguments, and proper citations ensure you avoid plagiarism and all the academic penalties that can result from it. The most commonly used citation format is the Modern Language Association (MLA) format, and it has specific guidelines for citing foreign-language sources.
MLA Format for Citing Foreign Sources
Cite in-text quotations the same way you would cite English-language sources. The MLA's standard format for in-text citations is to demarcate the cited text in quotation marks, followed by the author's surname and the page number(s) in parentheses at the end of the quote, using this form: "quoted text" (Author's surname, page numbers).
Create a comprehensive bibliography of all works cited, and ensure each entry is listed using proper MLA format. The standard practice is to list all works in alphabetical order on your "Works Cited" or "Supplementary Reading" appendix. This appendix is where you will list works you consulted but did not directly quote from in the body of your paper. For books, the standard form is as follows: Author's Surname, Author's First Name. Title of Work (in bold type or italics). Place of publication: publisher, edition (if there are multiple editions), year of publication.
List all foreign language sources in your "Works Cited" and/or "Supplemental Reading" section(s) in alphabetical order alongside all English-language sources; do not create a separate section for sources written in a foreign language. According to the MLA, alphabetizing foreign surnames should be done according to the first letter of the last name, even if it's a compound last name, regardless of whether it's a capital letter or a lower-case letter. For example, the name "Jorge de los Reyes" would appear as "de los Reyes, Jorge" in your bibliography and in-text citations.
Cite translated works, if you're using them, by including the name of the translator after the title of the book in your Works Cited or Supplemental Reading section(s). Thus, MLA style guidelines for this type of entry are as follows: Original author's surname, original author's first name. Title of work (in bold or italics). Trans: Name of translator, in first name-last name form. Place of publication: publisher, year of publication.