I do not understand from what did the problem Some russian ethnographer could collect the russian song on territory of the Ukraine Koshits collected ukrainian song on Kuban region The phrase Cossacks song not quite exact On Kuban veins not only Cossacks but also Inogorodnie which ossacks were not Besides Cossack song were and on Ukrainian and in Russian We do not know collected Koshits song in Russian No no sources about this The phrase collecting Ukrainian songs in Kuban region to my mind more exact