Shulga, G., V. Shakels, S. Skudra, and V. Bogdanovs. 2015. “Modified Lignin As an Environmentally Friendly Surfactant”. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (August): 276-81. https://doi.org/10.17770/etr2011vol1.919.