[Äbele, G., Birkmane, K., Vimba, E., Klavina, G., RasinS, A., RiekstinS, I., Tabaka, L., Fatere, I., Jukna, J. (1978). Chorology of the Latvian flora [Хорология флоры Латвийской ССР. Редкие виды растений 1 группы охраны]. Zinatne, Riga. 80 pp. (in Russian).]Search in Google Scholar
[Andrušaitis, G. (Ed.) (2003). Red Data Book of Lama. Institute of Biology of University of Latvia, Riga. 691 pp.]Search in Google Scholar
[Anonymous (2000). Analytical Methods for Atomic A bsorbt ion Spectrometry. PerkinElmer Instruments LLC. Available at: http://www1.lasalle.edu/~prushan/Intrumental%20Analysis_files/AA-Perkin%20Elmer%20guide%20to%20all!.pdf (accessed 2 February 2017).]Search in Google Scholar
[Anonymous (2012). Nature data system OZOLS. Nature Conservation Agency. Available at: www.daba,gov.lv/public/lat/datil/dabas_datu_parvaldibas_sistema_ozols/ (accessed 12 February 2017).]Search in Google Scholar
[Arditti, J. (1992). Fundamentals of Orchid Biology. John Wiley & Sons, New York. 691 pp.]Search in Google Scholar
[Auniņš, A. (ed.) (2013). Eiropas Savienlbas aizsargajamie biotopi Latvija [European Union Protected Habitats in Latvia]. Ministry of Environmental Protection and Regional Development of the Republic of Latvia, Riga. 359 pp. (in Latvian).]Search in Google Scholar
[Cepurīte, B. (2005). Latvijas vaskularo augu flora. 7: Orhideju dzimta [Vascular Flora of Latvia. 7: Orchid family ]. University of Latvia, Riga. 71 pp. (in Latvian).]Search in Google Scholar
[Cribb, P. (1997). The genus Cypripedium. Timber Press, Portland, 301 pp.]Search in Google Scholar
[Dearnaley J. (2007). Further advances in orchid mycorrhizal research. My- corrhiza, 17 (6), 475-486.10.1007/s00572-007-0138-117582535]Search in Google Scholar
[Devillers-Treschuren, J. (1999). Action plan for Cypripedium calceolus Europe (Nature and Environment, No. 100). Council of Europe Publishing, Strasbourg, 58 pp.]Search in Google Scholar
[Fageria, N. K. (2009). The Use of Nutrients in Crop Plants. CRC Press, Boca Raton. 430 pp.]Search in Google Scholar
[Fowler, J., Cohen, L., Jarvis, P. (1998). Practical Statistics for Field Biology. 2nd edn. Wiley, Chichester. 259 pp.]Search in Google Scholar
[Jones, Jr, J. B., Wolf, B., Mills, H. A. (1991). Plant Analysis Handbook. Micro-Macro Publishing, Athens. 213 pp.]Search in Google Scholar
[Juškevičs, V., Mumieks, A., Misans J. (1999). Latvijas £eolo£iska karte [Geological Map of Latvia]. Ministry of Environmental Protection and Regional Development State Geological Survey, Riga. 52 pp.]Search in Google Scholar
[Kļaviņa, D, Grauda, D., Priede, A., Rashal, I. (2014). The habitat diversity and genetic variability of Cypripedium calceolus in Latvia. In: Papers of the 6th Planta Europa Conference on the Conservation of Plants 23-27 May 2011. Krakow, pp. 91-97.]Search in Google Scholar
[Kull, T. (1999). Cypripedium calceolus L. J. Ecol., 87, 913-924.10.1046/j.1365-2745.1999.00407.x]Search in Google Scholar
[Kull, T. (2003). Cypripedium calceolus L. Interpreting population trends through short-term and long-term monitoring. In: Monitoring of Threatened Vascular Plants in Estonia and Finland - Methods and Experiences (The Finnish Environment, 659). Helsinkji, pp. 71-78.]Search in Google Scholar
[Laiviņš, M., Krampis, I. (2004). Jauna augu un dzlvnieku karteSanas sistema Latvija [A new system of plant and animal mapping in Latvia]. In: Abstracts of 62th scientific conference of University of Latvia: Geography, geology, environmental science. Riga, pp. 82-83 (in Latvian).]Search in Google Scholar
[Liepa, I. (2003). Meza enciklopedija [Forest Encyclopaedia]. Zelta grauds, Riga, pp. 197-198 (in Latvian).]Search in Google Scholar
[Marschner, H. (1995). Mineral Nutrition of Higher Plants. Academic Press, London. 889 pp.]Search in Google Scholar
[McCormick, M. K., Jacquemyn, H. (2014). What constrains the distribution of orchid populations? New Phytologist, 202 (2), 392-400.10.1111/nph.12639]Search in Google Scholar
[Mihalchuk (2011). Structure and dynamics of Cypripedium calceolus populations in natural and technogenically dangerous landscapes of Belaruss Polesye. In: Ohrana ikultivirovanie orhideii. Materiali IXMezdunarodnoi naucnoi konferencii (Sankt-Peterburg, 26-30 September, 2011), Moskva, pp. 305-310. [Oxpana u Kyjibtnueupoeanue opxudeu. Mamepucuibi IX Mexcdytiapodtiou naymiou Koncfepennuu.] (in Russian)]Search in Google Scholar
[Mills, H. A., Jones Jr., J. B. (1996). Plant Analysis Handbook II. MicroMacro Publ. Athens, Georgia. 422 pp.]Search in Google Scholar
[Page, A. L., Miller, R. H., Keeney, D. R. (eds.) (1982). Methods of Soil Analysis. Pari 2. Chemical and Microbiological Properties. Wisconsin. 1159 pp.]Search in Google Scholar
[Nollendorfs, V. (1983). Sipolpuku meslosana [Fertilisation of bulbous flovers]. Avots, Riga. 168 pp. (in Latvian).]Search in Google Scholar
[Reshetjuk, O. V. (2011). Structural analysis of Cypripedium calceolus populations in Ukraine. In: Ohrana i kultivirovanie orhideii. Matej’iali IX Mezdunarodnoi naucnoi konferencii (Sankt-Peterburg, 26-30 September, 2011), Moskva, pp. 348-352. [Oxpana u Kyjibmueupoeanue opxudeu. Mamepucuibi IXMexdynapodnou naynnou Kompepem^uu.] (in Russian)]Search in Google Scholar
[Rinkis, G. J., Nollendorf, V. F. (1982). Macro and Micronutrients in Balanced Nutrition of Plants [PnHbKHC, T. 51., HojiJieHflopcj), B. O. C6ajiancupoeannoe numanue pacmenuu Maxpo- u MwcpoojieMenmaMU]. Zinatne, Riga. 202 pp. (in Russian).]Search in Google Scholar
[Riņķis, G., Ramane, H. (1989). Kd barojas augi [Plant Nutrition]. Avots, Riga. 151 pp. (in Latvian).]Search in Google Scholar
[Rinkis, G., Ramane, H., Kunicka, T. (1987). Methods of Soil and Plant Analysis [Phhi>khc, T. 51., PaMaHe, X. K., KymiuKaa, T. A. Memodbi aucuima none u pacmenuu]. Zinatne, Riga, 174 pp. (in Russian).]Search in Google Scholar
[Riņķis G., Ramane H., Paegle G., Kunicka T. 1989. Optimisation System and Diagnostic Methods of Plant Mineral Nutrition [Phhi>khc, Y. 5!., Paviane, X. K., Flaanie, Y. B, KyHHUKaa, T. A. CucmeMa onmuMU3au,uu u Memodbi duazHOcmwcu MuuepcuibHozo numanusi pacmenuu]. Zinatne, Riga. 196 p. (in Russian)]Search in Google Scholar
[Shefferson, R. P., Weis, M., Kull, T., Taylor, D. L. (2(K)5). High specificity generally characterizes mycorrhizal association in rare lady s slipper orchids, genus Cypripedium. Molecular Ecology, 14, 613-626.10.1111/j.1365-294X.2005.02424.x15660950]Search in Google Scholar
[Sheviak, C. J. (1983). United States terrestrial orchids: Patterns and problems. In: North American Terrestrial Orchids: Symposium II Proceedings and Lectures. Plaxton, E. H. (Ed.). Michigan Orchid Society, Michigan, MI, pp. 49-60.]Search in Google Scholar
[Zhang, S.-B., Hu, H., Xu, K., Li, Z.-R. (2006). Gas exchanges of three co-occurring species of Cypripedium in a schrubland in the Hengduan Mountains. Photosynthetica, 44 (2), 241-247.10.1007/s11099-006-0014-9]Search in Google Scholar
[Zhang S.-B., Hu, H., Xu, K., Li Z.-R. (2006a). Photosynthetic performances of five Cypripedium species after transplanting. Photosynthetica, 44 (3), 425-432.10.1007/s11099-006-0046-1]Search in Google Scholar