org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse English NikolayDobrolubov, portrait and signature Russian Николай Добролюбов.
https://creativecommons.org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse English NikolayDobrolubov, portrait Russian Николай Добролюбов.