Principle 1: Short quotations (fewer than 50 words) are generally enclosed in quotation marks «e.g.». Any quotation marks within such a quote are converted to a single mark (').
Principle 2: Longer quotations (50 words or more) and shorter quotations to which the author wishes to give special emphasis are set off from the text by being indented both right and left (without quotation marks) «e.g.».
Principle 3: Both forms of quotation are followed immediately by a citation to the quoted work. (With an indented quotation the citation is not part of the indented material, but begins flush with the left margin «e.g.».) When the quoted work itself includes a quotation, that quotation should if possible be attributed to the original work in a parenthetical clause. And when that quotation shows alterations or omissions that should be indicated with the parenthetical clause "(alteration in original)".
Principle 4: Changes to a quoted work are shown with square brackets and ellipses (" . . . ") «e.g.». When omitted material comes at the beginning of a quotation the omission is shown by capitalizing the first letter of the first quoted word and placing that letter in brackets rather than with ellipses. Changes in emphasis and omissions of citations or footnotes are indicated by parenthetical clauses.