Matisovs, Ivars. “ZĪDAIŅU MIRSTĪBA KĀ VIDES KVALITĀTES INDIKATORS LATGALĒ”. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference, vol. 1, June 1999, pp. 103-9, https://doi.org/10.17770/etr1999vol1.1896.