Riddoch, C. J., Andersen, L. B., Wedderkopp, N., Harro, M., Klasson-Heggebo, L., Sardinha, L. B., Cooper, A. R., & Ekelund, U.
2004
Physical activity levels and patterns of 9-and 15-yr-old European children
Medicine and Science in Sports and Exercise
36(1)
86-92
10.1249/01.MSS.0000106174.43932.92