Gaya APA
Harpstead, M, I., Hole, F, D.
(1980).
Soil Science Simplified
.
Amerika Utara:
IOWA STATE UNIVERSITY PRESS.
Gaya MLA
Harpstead, Milo, I., Hole, Francis, D.
"Soil Science Simplified".
Amerika Utara:
IOWA STATE UNIVERSITY PRESS,
1980.
Text.