Abbt Braun, G. & Frimmel, F. H. (1999). Basic characterization of Norwegian NOM samples similarities and differences. Environment International, 25 (2/3), 161 –180.
Alikhani, H. & Hemati, A. (2014). Effect of Vermicompost Enrichment with Chemical Fertilizer and Bacterial Treatments on Humification and Acid Humic Properties. Journal of Agricultural Science and Sustainable Production, 24 (1), 113- 125. (In Persian)
Aranganathana, L., Radhika Rajasreea, S. R. Sumana, T. Y. Remyaa, R. R. Gayathria, S. Jayaseelana, C.,Karthiha, M. G. & Gobalakrishnana, M. (2019). Comparison of molecular characteristics of Type A humic acids derived from fish waste and sugarcane bagasse co-compost influenced by various alkaline extraction protocols. Microchemical Journal, 149, 1-8.
Behravan, H. R., Voroney, P. Khorassani, R. Fotovat, A. Moezei, A. A. & Taghavi, M. (2019). Chemical and Spectroscopic Characterization of Humic Acids Extracted from Filter Cake using Different Basic Solutions. Society for Sugar Research and Promotion. Sugar Tech, 1-8.
Chen, Y., Senesi, N. & Schnitzer, M. (1977). Information provided on humic substances by E4 /E6 ratios. Soil Science Society of American Journal, 41, 352 –358.
Demirbas, A., Yakup, K. & Huseyin, D. (2006). Humic Substances and Nitrogen-Containing Compounds from Low Rank Brown Coals, Energy Sources Part A: Recovery, Utilization, and Environmental Effects, 28 (4), 341-351.
Doskočil, L., Burdíková-Szewieczková, J. Enev, V. Kalina, L. & Wasserbauer, J. (2018). Spectral characterization and comparison of humic acids isolated from some European lignites. Fuel, 213,123–132.
Eshwar, M., Srilatha, M. Bhanu Rekha, K. & Harish Kumar Sharma, S. (2017). Characterization of humic substances by functional groups and spectroscopics methods. International Journal of Current Microbiology and Applied Sciences, 6 (10), 1768- 1774.
Fong, S.S., Seng, L., Chong, W.N., Asing, J., Faizal, M., Nor, M. & Mohd Pauzana, A.S. (2006). Characterization of the coal derived humic acids from Mukah, Sarawak as soil conditioner. Journal of the Brazilian Chemical Society, 17(3), 582–587.
Fuentes, M., Baigorri, R. Gonzalez-Gaitano, G. & Garcia-Mina, J. M. (2016). New methodology to assess the quantity and quality of humic substances in organic materials and commercial products for agriculture. Journal of Soil Sediments, 18, 1-11.
Giovanela, M., Crespo, J.S., Antunes, M., Adametti, D.S. & Fernandes, A.N. (2010). Chemical and spectroscopic characterization of humic acids extracted from the bottom sediments of a Brazilian subtropical microbasin. Journal of Molecular Structure, 981(1–3), 111–119.
Gondar, D., Lopez, R. Fiol, S. Antelo, J. M. & Arce, F. (2005). Characterization and acid–base properties of fulvic and humic acids isolated from two horizons of an ombrotrophic peat bog. Geoderma, 126, 367–374.
Gonzalez-vila., F. J. & Martin, F. (1985). Chemical strucral characteristics of humic acids extracted from composted municipal refuse. Agriculture, Ecosystems and Environment, 14, 267-278.
Hanc, A., Enev, V. Hrebeckova, T. Klucakova, M. & Pekar, M. (2019). Characterization of humic acids in a continuous-feeding vermicomposting system with horse manure. Wast Management, 99, 1–11.
Hoseini, S., Hejazi Mehrizi, M. Sarcheshmehpour, M. & Fekri, M. (2017). Comparison of some spectrophotometric ratios of humic acids extracted from plant residues compost and organic fertilizers. 15 th of Soil Science Congress of Iran. Isfahan University of Technology. (In Persian)
Ibrahim, M. I. M., Awad, E. A. M. Dahdouh, S.M.M. El- Etr,W. M. T. & Ibrahim, A. S. M. (2019). Characterization of some organic materials sources and analysis of the humic acids extracted from them. Zagazig Journal of Agricultural Research, 46 (3), 685- 698.
Kononova, M. M. (1966). Soil organic matter. 2nd ed. Pergamon, Oxford, UK.
Kumada, K. (1965). Studies on the colour of humic acids: part 1 on the concepts of humic substances and humification. Soil Science and Plant Nutrition, 11, 1116.
Kumada, K. (1987). Chemistry of soil organic matter, first ed., Japan Scientific Societies Press, Tokyo, 1987, p. 241.
Kumada, K. & Kawamura, Y. (1968). Viscos metric characteristics of humic acid. Soil Science and Plant Nutrition, 14, 190–197.
Li, X., Xing, M. Yang, J. & Huang, Z. (2011). Compositional and functional features of humic acid-like fractions from vermicomposting of sewage sludge and cow dung. Journal of Hazardous Materials, 18, 740–748.
Malakouti, M. J. (2014). Optimum ferilizer consumption recommendation for Agricultural Products in Iran. Mobaleghan Publisher. Pages, 348. (In Persian).
Omar, M. M., Taha A. A. & Abbas, A. E. (2018). Physicochemical characteristics of humic and fulvic acids extracted from different feedstocks. Soils Dept. Fac. of Agric., Mansoura Univ., Egypt. 9 (7), 277 – 281.
Page, A. L. 1982. Methods of soil analysis. Agronomi 9, ASA, SSSA, Madison, Wiscosin, USA.
Qi, B. C., Aldrich, C. and Lorenzen, L. (2004). Effect of ultra-sonication on the humic acids extracted from lignocellulose substrate decomposed by anaerobic digestion. Chemical Engineering Journal, 98, 153-163
Rajashekhar, D., Srilantha, M. Chandrasekhar Rao, P. Harish Kumar Sharma, S. & Bhanu Rekha, K. (2017). Functional and spectral characterization of humic fractions obtained from organic manures. International Journal of Pure and Applied Bioscience, 5 (6), 1254- 1259.
Sanchez-Monedero, M. A., Roig, A. Cegarra, J. Bernal, M. P. & Paredes, C. (2002). Effects of HCl-HF purification treatment on chemical composition and structure of humic acids. European Journal of Soil Science, 53, 375-381.
Sarlaki, A., Sharif pa ghaleh, A. Kianmehr, M. H. & Shakiba, N. (2017). Spectral, structural and chemical study of humic acids extracted from coals in Iranian mines. Iranian Journal of Soil and Water Research, 48 (5), 1145- 1158. (In Persian)
Shahbazi, K., Marezi, M. & Tabakhian, SH. (2019). The evaluation of methods for determination of humic and fulvic acids in fertilizer materials. Journal of Land Management, 7 (1), 97-114. (In Persian)
Swift, R. S. (1996). Organic matter characterization. In Methods of soil analysis, part 3: Chemical methods, ed. D. L. Sparks, Madison, Wisc.Soil Science Society of America, 1011–1069.
Tale Farahi, F. (2014). Investigation of humic acids extracted from sludge, biochar and animal manure on sunflower yield in calcareous soil. MSc Thesis of Soil Science. Zabol University. (In Persian)
Wali, A., Ben Salah, I. Zerrouki, M. Choukchou-Braham, A. Kamoun, Y. & Ksibi, M. (2019) .A novel humic acid extraction procedure from Tunisian lignite. Euro-Mediterranean Journal for Environmental Integration, 4 (24), 1-9.
Weber, J.W., McGinley, P.M. & Katz, L. E. (1992). A distributed reactivity model for sorption by soils and sediments. 1. Conceptual basis and equilibrium assessments. Environmental Science & Technology, 26, 1955 – 1962.