Gaya APA
Roskill, . (1980).
Roskills Directosy of Sources for Metals and Minerals Data .
London:
Roskill Information Services Ltd..
Gaya MLA
Roskill, .
"Roskills Directosy of Sources for Metals and Minerals Data".
London:
Roskill Information Services Ltd.,
1980.
Text.