Studies of soil penetration by disc coulters of direct drills /
Gray, A. G.(Agricultural engineer),author.
MacIntyre, D.(Duncan),-2015,author.
Scottish Institute of Agricultural Engineering.
"Not for publication."--title-page.
"Scottish Institute of Agricultural Engineering."--at the head of the cover.
Report dated February 1983.
Includes bibliographical references (page 10).
Drills (Planting machinery)