(1990). The 1990 World Book year book: The annual supplement to the World Book encyclopedia. World Book.
Чикаго маягийн жагсаалтThe 1990 World Book Year Book: The Annual Supplement to the World Book Encyclopedia. Chicago: World Book, 1990.
MLA ишлэлThe 1990 World Book Year Book: The Annual Supplement to the World Book Encyclopedia. World Book, 1990.
Warning: These citations may not always be 100% accurate.