Bulgarian Wikipedia has an article on: <span class="searchmatch">Янтра</span> Wikipedia bg Attested Ancient Greek Ἄθρυς (Áthrus), later also Latin Iatrus, Ieterus. Ultimately from Thracian...
Bulgarian Wikipedia has an article on: Етър Wikipedia bg Doublet of <span class="searchmatch">Янтра</span> (Jantra). Етър • (Etǎr) a museum in Bulgaria...
English Wikipedia has an article on: Yantra Wikipedia From Bulgarian <span class="searchmatch">Янтра</span> (Jantra). Yantra A river in Bulgaria...
(jantár) Carpathian Rusyn: янта́рь (jantárʹ) Ukrainian: янта́р (jantár); <span class="searchmatch">я́нтра</span> f (jántra) (dialectal) ^ Melnychuk, O. S., editor (2012), “янта́р”, in Етимологічний...
(jantár) Carpathian Rusyn: янта́рь (jantárʹ) Ukrainian: янта́р (jantár); <span class="searchmatch">я́нтра</span> f (jántra) (dialectal) → Middle Russian: онта́рь (ontárʹ), оньта́рь (onʹtárʹ)...