APA Style
National Geographic. (2012).
USA:
National Geographic Society.
Chicago Style
National Geographic.
Vol.221/No.4/April 2012.
USA:
National Geographic Society,
2012.
Books.
MLA Style
National Geographic.
Vol.221/No.4/April 2012.
USA:
National Geographic Society,
2012.
Books.
Turabian Style
National Geographic.
USA:
National Geographic Society,
2012.
Books.