Ня́коймие откра́днал кни́гата! ― Njákoj mi e otkrádnal knígata! ― Someone has stolen my book!
Ви́ждамня́когонаврата́та. ― Víždam njákogo na vratáta. ― I see someone at the door.
Usage notes
The accusative and (archaically) the dative forms are used only when ня́кой serves as a pronoun, not as a determiner modifying another noun. In informal Bulgarian the nominative form is often used instead of the accusative and prepositional ones (Ня́кой ви́ждам, с ня́кой разгова́рям). This usage is not considered standard.