Lazdiņa, Dagnija, Andis Lazdiņš, Zigurds Kariņš, and Visvaldis Kāposts. 2007. “Effect of Sewage Sludge Fertilization in short‐rotation Willow Plantations”. Journal of Environmental Engineering and Landscape Management 15 (2):105-11. https://doi.org/10.3846/16486897.2007.9636916.