This is the 8263rd most frequent Russian word.
мартунинского
"Мартунинского" is the genitive or adjective form related to "Martuni," a town or region name, meaning "of Martuni" or "Martuni's."
The word 'мартунинского' here is used as an adjective in the genitive case to describe a newspaper belonging or pertaining to Martuni.
Я прочитал интересную статью в мартунинском газете.
I read an interesting article in the Martuni newspaper.
In this sentence, 'мартунинского' describes an artist from Martuni, used in the accusative singular case.
Мы посетили мартунинского художника, известного своими пейзажами.
We visited a Martuni artist known for his landscapes.
Here, 'мартунинских' is used in the genitive plural form to describe works associated with Martuni.