Gaya APA

Swanson, C, P., Umlauf, I, L, H. (NULL). The world almanac & book of facts 1981 . New: New York: Newspaper; 1981.

Gaya MLA

Swanson, Carl, P.., Umlauf, I., Lane,, Hana. "The world almanac & book of facts 1981". New: New York: Newspaper; 1981, NULL. Text.