Citazione Stile APA (7a Edizione)

Engelbrektson, S., & Greenleaf, P. (1969). Let's explore outer space: Elementary research problems in space science. Sentinel Book Publishers.

Citazione stile Chigago Style (17a edizione)

Engelbrektson, Sune, e P. Greenleaf. Let's Explore Outer Space: Elementary Research Problems in Space Science. New York: Sentinel Book Publishers, 1969.

Citatione MLA (9a ed.)

Engelbrektson, Sune, e P. Greenleaf. Let's Explore Outer Space: Elementary Research Problems in Space Science. Sentinel Book Publishers, 1969.