@misc{[Opitz_Richard]_[A_[before,
 author={[Opitz, Richard]},
 copyright={Rights Reserved - Restricted Access},
 howpublished={online},
 year={[before 1918]},
 title={[A portrait of a uhlan] [An iconographic document]},
 keywords={1st World War (1914-1918), Imperial German Army, ethnography, material culture, social culture, army, man, uhlan, uhlan's uniform, Potsdam (Germany)},
}