APA (7th ed.) Citation

Alliluyeva, S., & Johnson, P. (1968). 20 letters to a friend. World Books.

Chicago Style (17th ed.) Citation

Alliluyeva, Svetlana, and Priscilla Johnson. 20 Letters to a Friend. London: World Books, 1968.

MLA (9th ed.) Citation

Alliluyeva, Svetlana, and Priscilla Johnson. 20 Letters to a Friend. World Books, 1968.

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