<a href="https://en.wikipedia.org/wiki/Adam_Prochnik" class="extiw" title="en:Adam Prochnik">Adam Próchnik</a> (1892-1942) -  Polish socialist activist, politician and historian.
unknown-anonymous
„Pobudka” 1927 nr 39  see also <a rel="nofollow" class="external free" href="https://www.ipsb.nina.gov.pl/a/foto/adam-prochnik">https://www.ipsb.nina.gov.pl/a/foto/adam-prochnik</a>