Gaya APA
Siregar, E. (2008).
National Geographic Indonesia: Juni 2008 (Misteri Tugu Purba) .
Jakarta:
National Geographic Society.
Gaya MLA
Siregar, Elwin.
"National Geographic Indonesia: Juni 2008 (Misteri Tugu Purba)".
Jakarta:
National Geographic Society,
2008.
Text.