In total Matisen discovered and named about 40 islands of the Nordenskiöld group ; he also arranged the archipelago into the following four main subgroups : Vilkitsky Islands , Pakhtusov Island s , Tsivolko Islands and Litke Islands .
ADP ADJ PROPN VERB CCONJ VERB ADP NUM NOUN ADP DET PROPN NOUN ; PRON ADV VERB DET NOUN ADP DET VERB NUM ADJ NOUN : PROPN NOUN , PROPN PROPN PROPN , PROPN PROPN CCONJ PROPN PROPN .