Shulga, G., V. Shakels, S. Skudra, and V. Bogdanovs. “Modified Lignin As an Environmentally Friendly Surfactant”. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (August 5, 2015): 276–281. Accessed April 28, 2024. https://journals.ru.lv/index.php/ETR/article/view/919.