@article{ref1,
title="Development of physical leisure activity in the transition of adolescents from school to vocational education",
journal="Arztliche Jugendkunde",
year="1987",
author="Hartmann, B. and Kryk, W. and Waga, N. C.",
volume="78",
number="4",
pages="269-274",
abstract="<p>[Abstract unavailable]</p><p>Language: de</p>",
language="de",
issn="0001-9518",
doi="",
url="http://dx.doi.org/"
}