Ecological study of playground space and physical activity among primary school children
Anne C Grunseit, Blythe Jane O'Hara, Bradley Drayton, Vincent Learnihan, Louise L Hardy, Eve Clark, Paul Klarenaar, Lina Engelen
BMJ Open Jun 2020, 10 (6) e034586; DOI: 10.1136/bmjopen-2019-034586