• Bento, G., & Dias, G. (2017). The importance of outdoor play for young children's healthy development. Porto Biomedical Journal, 2(5), 157-160.  
• Finnish Education Evaluation Centre (2020). Varhaiskasvatuksen laatu arjessa. Varhaiskasvatussuunnitelmien toteutuminen päiväkodeissa ja perhepäivähoidossa. Finnish Education Evaluation Centre. 
• Finnish National Agency for Education (2022). National core curriculum for early childhood education and care. Publications of the Ministry of Education and Culture. 
• Finnish National Agency for Education (2014). National core curriculum for pre-primary education. Publications of the Ministry of Education and Culture. 
• Hewes, J. (2007). The Value of Play in Early Learning: Towards a Pedagogy. In the book (eds.) Jambor, T & Van Gils, J. Several Perspectives on Children´s Play. Scientific Reflections for Practitioners. Antwerp – Apeldoorn: Garant, 119-132.  
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• Palmer, J.A. (1998). Environmental Education in the 21st Century: Theory, Practice, Progress and Promise. London: Routledge.  
• Sandseter, E. B. H, Cordovil, R., Løge Hagen, T., & Lopes, F. (2020). Barriers for Outdoor Play in Early Childhood Education and Care (ECEC) Institutions: Perception of Risk in Children’s Play among European Parents and ECEC Practitioners. Child Care in Practice, 26(2), 111-129. 
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More information:

• Ryan, Browning, Clancy, Andrews, Kallianpurkar (2014). Biophilic Design Patterns: Emerging Nature-Based Parameters for Health and Well-Being in the Built Environment. International Journal of Architectural Research.  
• An, Colarelli, O'Brien, Boyajian (2016). Why We Need More Nature at Work: Effects of Natural Elements and Sunlight on Employee Mental Health and Work Attitudes.  PLoS ONE.