1. Doran, J.W., Sarrantonio, M. & Liebig, M.A., (1996). Soil health and sustainability. In: Sparks, D.L. (Eds.), Advances in Agronomy. Academic Press, pp. 1-54.
2. Elliot, E.T., (1997). Rationale for developing bioindicators of soil health. In: Pankhurst, C.E., Doube, B.M. & Gupta, V.V.S.R. (Eds.), Biological Indicators of Soil Health. CAB International, pp. 49-78.
3. Doran, J.W., Safley, M., (1997). Defining and assessing soil health and sustainable productivity. In: Pankhurst, C.E., Doube, B.M., Gupta, V.V.S.R. (Eds.), Biological Indicators of Soil Health. CABI Publishing, Wallingford, UK, pp. 1-28.
4. Pankhurst, C.E., Doube, B.M. and Gupta, V.V.S.R., 1997. Biological indicators of soil health: Synthesis. In: Pankhurst, C.E., Doube, B.M. & Gupta, V.V.S.R. (Eds.), Biological Indicators of Soil Health. CAB International, pp. 419-435.
5. Haitova, D. and Bileva T. (2011). Influence of different fertilizer types of zucchini (Cucurbita pepo) on the structure of nematode communites. “Comm. in Agric. and Appl. Biol. Scien.”, Ghent University, vol. 76 (3): 341 – 345.