1. lung function testing;PhStandard, Quanjer;Bull Eur Physiopathol Respir
2. Notes on the statistics ofgrowth standards;Healy, M.J.R.;Ann Hum Biol,1974
3. Statistics with confidence: confidence intervals and statistical guidelines;Gardner, M.J.,1989
4. Presentation of variability;Altman, D.G.; Gardner, M.J.;Lancet,1986
5. Statistical methods in medical research;Armitage, P.; Berry, G.,1987