ASAE Standards (1990). S313.2. Soil Penetrometer. 37th Ed.St. Joseph, MI:ASAE, pp. 820-821
ASTM (1991). Standard D2216-90. Methods for laboratory determination of moisture content of soil. In Annual Book of ASTM Standards. 0408: 278-281. Philadelphia, PA: American Society for Testing and Materials.
Abd El-Wahab, M.K. (1994). Minimum tillage by a simple combination. Misr Journal of Agricultural Engineering, 11(1):711-724.
Chase, L. W. (1942). A study of subsurface tiller blades. Agricultural Engineering 23:43-45, 50.
Dowell, F.E., Siemens J.C. and Bode L. E. (1988). Cultivator speed and sweep spacing effects on herbicide incorporation. Transactions of the ASAE 31(5):1315-1321.
Eidet, J. H. (1974). Effect of varied approach angle on high speed mouldboard plow performance. Unpublished M.Sc. thesis. Iowa State University, Ames, IA.
Ellison, W. D. (1947). Soil erosion studies- Part II. Agricultural Engineering 28:197-201.
Goryachkin, V. P. (1968). Collected works in three volumes. Ed. N. D. Luchinskii. Translated 1972. Jerusalem, Israel: Ketter Press.
Hanna, H.M., Erbach D.C., Marley S.J. and Melnin S.W. (1993a). Comparison of the Goryachkin theory to soil flow on a sweep. Transactions of ASAE 36(2):293-299.
Hanna, H.M., Erbach D.C., Marley S.J. and Melnin S.W. (1993b). Changes in soil microtopography by tillage with a sweep. Transactions of ASAE. 36(2): 301-307.
Lobb, D. A. and Kachanoski R. G. (1997). Quantification of tillage translocation and tillage erosion. Presented at the tillage translocation and tillage erosion: An International Symposium, Part of the 52nd Annual Conference of the Soil and Water Conservation Society, Toronto, ON, Canada, pp. 189-209
Pimentel, D. (1993). World soil erosion and conservation. Cambridge, NY: Cambridge University Press.
Sharifat, K. and Kushwaha R. L. (1997). Soil translocation by two tillage tools. Canadian Agricultural Engineering 39(2):77-84.
Sibbesen, E., and Anderson C. E. (1985). Soil movement in long-term experiments as a result of cultivations: II. How to estimate the two-dimentional movement of substances accumulating in the soil. Journal of Experimental Agriculture. (21): 109-117.
Söhne, W. (1960). Suiting the plow body shape to higher speeds. National Institute of Agricultural Engineering Translation No. 101(12):51-62.
Turkelboom, F., Poesen J., Ohler I., Van Keer K., Ongprasert S. and Vlassak K. (1996). Assessment of tillage erosion rates on steep slopes in northern Thailand. Catena 29: 29-44.