1. Alef, K., & Nannipieri, P. (1995). Enzyme activities. In P. Nannipieri & K. Alef (Eds.), Methods in applied soil microbiology and biochemistry pp (pp. 311–375). London: Academic Press.
2. Azarbad, H., van Gestel, C. A. M., Niklińska, M., Laskowski, R., Röling, W. F., & van Straalen, N. M. (2016). Resilience of soil microbial communities to metals and additional stressors: DNA-based approaches for assessing “stress-on-stress” responses. International Journal of Molecular Sciences, 17(6), 933.
3. Baaru, M.W., Mungendi, D.N., Bationo, A., Verchot, L., & Waceke, W. (2007). Soil microbial biomass carbon and nitrogen as influenced by organic and inorganic inputs at Kebete, Kenya. In: Batiano A. (eds.) Advances in integrated soil fertility management in Sub- Saharan Africa: challenges and oppurtunities, pp 827-832.
4. Balicka, N., & Varanka, M. W. (1978). Effect of industrial pollution of air on soil microflora. Advances of Agricultural Sciences Problem Issues, 206, 17–27.
5. Błońska, E. (2015). Effect of stand species composition on the enzyme activity and organic matter stabilization in forest soil; scientific papers of University of Agriculture in Krakow no. 527; University of Agriculture in Krakow: Kraków, Poland, volume 404.