Citation, Documentation of Sources
Q. When including a direct quote translated into English from a source written in a foreign language, how should this be indicated? Is it necessary to make it clear that the author of the work in which the source is cited, rather than the author of the source or a translator, has translated the quote from the original? If so, how?
A. Yes; in a scholarly publication this is required. You can write in parentheses “translated by the author” or “Smith’s translation” or whatever applies. If there are many such translations you can explain in a note: “All quotations of Petroski are Smith’s translations unless stated otherwise.”