@misc{_Rules,
 howpublished={online},
 publisher={Polski Rejestr Statków},
 language={eng},
 type={e-książka},
 title={Rules for classification and construction of inland waterways vessels. Pt. 4, Stability and freeboard, March 2016},
 keywords={statki rzeczne, przepisy bezpieczeństwa, normy, stabilność},
}