How can I find Martynovka, Russia?

It is important to clearly understand the location of the events: The vital records in Russian Empire were kept in handwritten books, which are rarely digitized and/or indexed, so in order to search successfully we need to be certain of the location of events (and have a clear idea how this location is documented).

For example, Rostov eparchy has today around 130 churches, and it was more than that in 1912, each with separate records. There are at least a dozen places called Martynowka in the modern day Ukraine, evenly spread around the whole country. There are 30+ German-inhabited places from Odessa to Saratov (1600 km apart) similarly named after Ekaterina the Great, who is thought to be the main sponsor of German immigration to Russia.