Lazdiņa, Dagnija, Andis Lazdiņš, Zigurds Kariņš, and Visvaldis Kāposts. “Effect of Sewage Sludge Fertilization in Short‐rotation Willow Plantations”. Journal of Environmental Engineering and Landscape Management 15, no. 2 (June 30, 2007): 105-111. Accessed July 23, 2019. https://journals.vgtu.lt/index.php/JEELM/article/view/7623.