APA Edition Citation

Gregersen , E. e. (2010). Manned spaceflight. Britannica Educational Services.

Chicago Edition Citation

Gregersen , Erik etc. Manned Spaceflight. New York: Britannica Educational Services, 2010.

MLA Edition Citation

Gregersen , Erik etc. Manned Spaceflight. Britannica Educational Services, 2010.

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