From the Wikipedia page 
Plyussky District (Russian: Плю́сский райо́н) is an administrative and municipal district (raion), one of the twenty-four in Pskov Oblast, Russia. It is located in the northeast of the oblast and borders with Slantsevsky District of Leningrad Oblast in the north, Luzhsky District of Leningrad Oblast in the northeast, Shimsky District of Novgorod Oblast in the east, Strugo-Krasnensky District in the south, and with Gdovsky District in the west. The area of the district is 2,767 square kilometers (1,068 sq mi). Its administrative center is the urban locality (a work settlement) of Plyussa.