Quotations within quotations

Sometimes you will quote a passage that itself contains quotation marks.

SOURCE

　　But though I was initially disappointed at being categorized as an extremist, as I continued to think about the matter I gradually gained a measure of satisfaction from the label. Was not Jesus an extremist for love: "Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you." Was not Amos an extremist for justice: "Let justice roll down like waters and righteousness like an ever-flowing stream."

　　Martin Luther King, Jr., "Letter from Birmingham Jail." 1963. What Country Have I? Political Writings by Black Americans, ed. Herbert J. Storing （New York: St. Martin's Press, 1970）, 125-26.

　　How you handle this depends on whether the main quotation is long enough to be set off or not. If it is a short passage that you are incorporating into your text, then, then you will surround the main quotation with double quotation marks and mark the inner quotation with single quotation marks:

　　Instead of denying the accusation that he is an extremist, King embraces it: "As I continued to think about the matter I gradually gained a measure of satisfaction from the label. Was not Jesus an extremist for love: 'Love your enemies, bless them that curse you, do good to them that hate you . . .' " （125-6）.

　　If it's a set-off quotation, then put the usual double-quotation marks around the inner quotation （since quotation marks aren't put around set-off quotations）.

　　For more on quotations see the upcoming specific documentation styles （MLA, APA, Chicago, and CBE）.