title: Splitting hairs.
authors.affiliation: Middlesex Hospital, Mortimer Street, London W1T 3AA, UK. R.Viner@ich.ucl.ac.uk
authors.forename: R
authors.initials: R
authors.lastname: Viner
mesh_terms: D000367:Age Factors; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008572:Menarche / Q000502:physiology; D015588:Observer Variation; D011627:Puberty / Q000502:physiology*