Physical activity in child-care centers: do teachers hold the key to the playground?
Kristen A. Copeland, Cassandra A. Kendeigh, Brian E. Saelens, Heidi J. Kalkwarf, Susan N. Sherman
Health Educ Res. 2012 February; 27(1): 81–100. Published online 2011 July 29. doi: 10.1093/her/cyr038