APA (7th ed.) Citation

United States. Coast Guard. (1921). Index for circular letters. [publisher not identified].

Chicago Style (17th ed.) Citation

United States. Coast Guard. Index for Circular Letters. [Washington]: [publisher not identified], 1921.

MLA (9th ed.) Citation

United States. Coast Guard. Index for Circular Letters. [publisher not identified], 1921.

Warning: These citations may not always be 100% accurate.