B 1.2 (p. 4): Bluepages rule for Introductory Signals
B 1.3 (p. 5): Bluepages rule for Explanatory Parentheticals
Rule 1 (p. 57): Rule for Structure and Use of Citations
The main purpose of citations is to provide your reader with an easy way to find the authority for which you are referencing. Bluebook Rule 1 states that these citations are enclosed in citation sentences, introduced by signals. Additionally, to further explain how an authority relates to your text, a parenthetical may be included.