From Wikipedia (
https://en.wikipedia.org/wiki/Republic_of_Serbian_Krajina):
"The Republic of Serbian Krajina or Serb Republic of Krajina (Serbo-Croatian: Република Српска Крајина / Republika Srpska Krajina or РСК / RSK, pronounced [rɛpǔblika sr̩̂pskaː krâjina]), known as the Serbian Krajina[a] (Српска Крајина / Srpska Krajina) or simply Krajina, was a self-proclaimed Serb proto-state,[5][6] a territory within the newly independent Republic of Croatia (formerly part of SFR Yugoslavia), which it defied, and which was active during the Croatian War of Independence (1991–95). It was not recognized internationally. The name Krajina ("Frontier") was adopted from the historical Military Frontier of the Habsburg Monarchy and Austria-Hungary, which had a substantial Serb population and existed up to the late 19th century. The RSK government waged a war for ethnic Serb independence from Croatia and unification with FR Yugoslavia and Republika Srpska (in Bosnia and Herzegovina).[7]"
On Numista, you can find these under Banknotes › Croatia › Krajina, Serb Republic of:
https://en.numista.com/catalogue/krajina-republic-banknotes-1.html
The ones listed under Bosnia and Herzegovina (
https://en.numista.com/catalogue/srpska-republic-banknotes-1.html), while having a similar design, say НАРОДНА БАНКА СРПСКЕ РЕПУБЛИКЕ БОСНЕ И ХЕРЦЕГОВИНЕ / NARODNA BANKA SRPSKE REPUBLIKE BOSNE I HERCEGOVINE on them.