APA
John Green, . (2017). Turtles all the way down. United Kingdom: Penguin Books.
Chicago
John Green, . 2017. Turtles all the way down. United Kingdom: Penguin Books.
Harvard
John Green, . (2017). Turtles all the way down. United Kingdom: Penguin Books.
MLA
John Green, . Turtles all the way down. United Kingdom: Penguin Books. 2017.