Vircavs, Magnuss, and Valdis Vircavs. “VIDES BŪTĪBA”. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (June 20, 1999): 233–238. Accessed April 23, 2025. https://journals23.rta.lv/index.php/ETR/article/view/1868.