Do istoriï ukraïnsʹkoho kozacʹkoho ruchu v emihraciï lysty Ivana Poltavcja-Ostrjanyci do Adolʹfa Hitlera = K istorii ukrainskogo kazackogo dviženija v ėmigracii : pisʹma Ivana Poltavca-Ostrjanicy Adolʹfu Gitleru = To the history of the Ukrainian cossack movement in exile : Ivan Poltavets-Ostryanytsa’s letters to Adolf Hitler - Burim, Dmytro Vasylʹovyč (2013)