APA (7th ed.) Citation

Library of Congress. Research Services. (1921). Classification: Class R, Medicine. GPO.

Chicago Style (17th ed.) Citation

Library of Congress. Research Services. Classification: Class R, Medicine. [Washington]: GPO, 1921.

MLA (9th ed.) Citation

Library of Congress. Research Services. Classification: Class R, Medicine. GPO, 1921.

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