Lawrence E. Armstrong, Carl M. Maresh, John W. Castellani, Michael F. Bergeron, Robert W. Kenefick, Kent E. LaGasse, Deborah Riebe,
Urinary indices of hydration status. International Journal of Sport Nutrition. ,vol. 4, pp. 265- 279 ,(1994) ,
10.1123/IJSN.4.3.265