Biological maturation, body composition, and growth of female gymnasts and control groups of schoolgirls and girl swimmers, aged 8 to 14 years: a cross-sectional survey of 1064 girls. - Peltenburg,A.L.; Erich,W.BM.; Bernink,M.JE.; Zonderland,M.L.; Huisveld,I.A. (Int J Sports Med, 1984)