@article{ref1,
title="Hygienic principles of organizing extracurricular activities of students",
journal="Gigiena i Sanitariia",
year="1971",
author="Iappo, T. A.",
volume="36",
number="5",
pages="34-39",
abstract="<p>[Abstract unavailable]</p><p>Language: ru</p>",
language="ru",
issn="0016-9900",
doi="",
url="http://dx.doi.org/"
}