Gaya APA
B.STEPHENSON, S. et al (1982).
THE REGIONAL GEOCHEMICAL ATLAS OF NORTHERN SUMATRA .
Bandung:
Pusat Sumber Daya Geologi.
Gaya MLA
B.STEPHENSON, S,A. et al.
"THE REGIONAL GEOCHEMICAL ATLAS OF NORTHERN SUMATRA".
Bandung:
Pusat Sumber Daya Geologi,
1982.
Logam.