APA (7th ed.) Citation

(1991). The World book health and medical annual 1991. World book.

Chicago Style (17th ed.) Citation

The World Book Health and Medical Annual 1991. Chicago: World book, 1991.

MLA (9th ed.) Citation

The World Book Health and Medical Annual 1991. World book, 1991.

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