1. Eurostat European statistical commission. Eurostat statistical book Forestry in the EU and the world 2011; 116.
2. State Forest Service Forest statistic's CD year 2013. Available: https://www.zm.gov.lv/valsts-meza-dienests/statiskas-lapas/publikacijas-un- statistika/meza-statistikas-cd?nid=1049#jump.
3. Zhu H.Y., Weng Y.H., Zhang H.G., Meng F.R. Major Comparing fast – and slow – growing provenances of Picea koraiensis in biomass, carbon parameters and their relationships with growth 2013:181-182.
4. Stibe U. Tree crown elements of quantitative indicators logging old–age spruce forest. Jelgava, 1976, 187.
5. Daugavietis M., Polis O., Korica A., Seleznovs J. Scotch pine – a natural raw material for high-quality biologically active substances,. Proceedings of The Latvia University of Agriculture 2012.