Determining the actual location of your ancestral village in the Transcarpathian region can be challenging. Two world wars and different political administrations mean that your village may have been known under several different names.
One of the most useful sources for locality determination is the 1877 Dvorzsák gazetteer. Unfortunately the RADIX portal hosting the digitized, sortable versions of the 1877 and 1913 gazetteers is no longer operational but should be available via the Wayback machine.
Below are some links to on-line gazetteers and other suggestions to help you determine the location of your ancestral village.
This is my version of the 1877 Dvorzak gazetteer in EXCEL format that I use for locality identification for the Infantry Regiment 5 project. Contains additional columns for current name and country and links to wikipedia entries. This is a copy of a working document that I use for determining the location names for the Infantry Regiment 5 project. It is not complete. Most useful for Bereg, Ung, Ugocsa and Maramaros varmegyes.
A book in Hungarian that documents the history of Transcarpathian placenames
The Hungarian Central Statistical Office has digitized a large collection of Gazetteers
The Adatbank group has a lot of interesting information including a useful gazetteer with German and Hungarian place names for Transylvania
A useful source of locality information can be the 'Schematizmus' documents issued by the Roman Catholic and Greek Catholic dioceses. These documents list the names of the main and affiliated churches in each diocese. The information often includes when the parish was founded, the name of the church, the name of the priest, , a summary of the religion followed by the inhabitants of the town or village.
Each diocese produced its own Schematizmus. However in 1842/1843 a 'Universal Schematizmus for Roman Catholic and Greek catholic dioceses was produced. This book has a good index.
The original digitized version was produced for the Klimotheca portal managed by the University of Pecs. This version is quite clunky to use as the the digitization technology was in its infancy. The version digitized by the Hungarian National Digital Archive (MaNDA) is easier to use.
The villages included in each parish did change occasionally , so it i worth seeking out other schematizmus. Try searching Google or digital libraries with 'Schematizmus (or schematismus) and the latin name of the diocese. For example Schematizmus Cassoviensis, for the Catholic diocese of Kassa (Kosice) in Slovakia.
The Hungarian Byzantine Church [Greek Catholic Church) (byzantinohungarica.com) has a comprehensive collection of greek catholic schematizmus. The earliest dates back to 1814. The 1913 Munkacs schematismus can be very useful for the Transcarpathian region.
Has some useful historical information on the historical structure of dioceses.
The Eotvos University has a listing of historical 1910 county maps and the Gonczy maps from the 1870's. It is useful to compare the place names in a region in both of these maps. Place names changed significantly. Many of these county (varmegye) maps are available in Hungarian wikipedia (hu.wikipedia.com). Use search term [Name of county] + varmegye.
The English version of wikipedia has very limited information on localities in Eastern Europe. to view national versions of wikipedia, type the country letter code followed by dot_wikipedia.org
If you are using Google Chrome, right click to get automatic translation
Hungarian wikipedia is very comprehensive. It often provides the historical names of the town or village. The issue with Hungarian wikipedia is that that you need to search using the modern Hungarian name of the town, as it was determined in 1913.
Genteam , the Austrian genealogy portal, has a useful gazetteer that has been expanded to include Austria, Czech, Slovak and Slovenia. It is free to join.