Gaya APA
Wyllie, D, C., Mah, C, W. (1974).
Rock Slope Engineering Civil and Mining 4th Edition .
New York:
The Institution of Mining and Metallurgy.
Gaya MLA
Wyllie, Duncan, C.., Mah, Christopher, W.
"Rock Slope Engineering Civil and Mining 4th Edition".
New York:
The Institution of Mining and Metallurgy,
1974.
Text.