Patterns of intense physical activity among 15- to 30-year-old Finns - Raitakari, O. T.; Taimela, S.; Porkka, K. V. K.; Leino, M.; Telama, R.; Dahl, M.; Viikari, J. S. A. (Blackwell Publishing Ltd, 1996)
http://dx.doi.org/10.1111/j.1600-0838.1996.tb00068.x
Keywords: WW-YZ; ZX-ZY