1. Resistance to penetration of fine probes in compressible soil;Farrell;Australian Journal of Soil Research,1966
2. Mechanical impedance to root growth: A review of experimental techniques and root growth responses;Bengough;Journal of Soil Science,1990
3. The cone penetrometer in relation to trafficability, compaction and tillage;Campbell,1991
4. The penetration of clays by fine probes and root tips;Cockroft;Australian Journal of Soil Research,1969
5. Soil mechanics in relation to tillage implements, and root penetration in lowland soils;Dexter,1986