From the Wikipedia page [1]
Zubtsovsky District (Russian: Зубцо́вский райо́н) is an administrative and municipal district (raion), one of the thirty-six in Tver Oblast, Russia. It is located in the south of the oblast and borders with Staritsky District in the north, Lotoshinsky District of Moscow Oblast in the northeast, Shakhovskoy District, also of Moscow Oblast, in the east, Gagarinsky District of Smolensk Oblast in the south, Sychyovsky District, also of Smolensk Oblast, in the southwest, and with Rzhevsky District in the west. The area of the district is 2,166.5 square kilometers (836.5 sq mi). Its administrative center is the town of Zubtsov.