APA Style
National geographic : Petra Vol.194 No.6. (1998).
Washington, D.C:
the National Geographic Society.
Chicago Style
National geographic : Petra Vol.194 No.6.
December 1998.
Washington, D.C:
the National Geographic Society,
1998.
Text.
MLA Style
National geographic : Petra Vol.194 No.6.
December 1998.
Washington, D.C:
the National Geographic Society,
1998.
Text.
Turabian Style
National geographic : Petra Vol.194 No.6.
Washington, D.C:
the National Geographic Society,
1998.
Print.