Verschuur, R., Zundert, A. v., Kemper, H. C., Ruskin, H., & Simkin, A. (1987). Longitudinal participation in sports in girls and boys in relation to physical fitness in their late teens and early twenties. The Amsterdam Growth and Health Study. Physical fitness and the ages of man, S. 59-82.

Verschuur, Robbert, Adrie van Zundert, Han C.G Kemper, Hillel Ruskin, and Ariel Simkin. "Longitudinal Participation in Sports in Girls and Boys in Relation to Physical Fitness in Their Late Teens and Early Twenties. The Amsterdam Growth and Health Study." Physical Fitness and the Ages of Man 1987: S. 59-82.

Verschuur, Robbert, et al. "Longitudinal Participation in Sports in Girls and Boys in Relation to Physical Fitness in Their Late Teens and Early Twenties. The Amsterdam Growth and Health Study." Physical Fitness and the Ages of Man 1987: S. 59-82.