- Baltic States: Estonia, Latvia, Lithuania
Cyndi's List for Baltic States (Estonia, Latvia & Lithuania) http://www.cyndislist.com/baltic.htm
Estonian Museum of Occupation https://www.vabamu.ee (includes casualty lists)
National Archives of Estonia https://www.ra.ee/vau/index.php/en/page/article/index?menuId=16
Latvian State Historical Archives (Raduraksti) https://www.arhivi.gov.lv/en/department/latvian-state-historical-archive
Discovering Latvian Roots http://www.celmina.com
Lithuanian Global Genealogy Society http://www.lithuaniangenealogy.org/
Lithuanian Toolkit https://www.familytreemagazine.com/heritage/lithuanian/lithuania-toolkit/ (Family Tree magazine) - Czech Republic & Slovakia
Cyndi's List for Czech Republic & Slovakia http://www.cyndislist.com/czech.htm
Czechoslovak Genealogical Society International https://cgsi.org
Czech Genealogy for Beginners http://czechgenealogy.blogspot.com/ (blog)
Czech Republic Genealogy http://www.genealogylinks.net/europe/czech_republic/
Slovak Republic Genealogy https://wgwslovakia.wordpress.com - Hungary
Researching Hungarian ancestors http://www.barbsnow.net/Hungary.htm
Hungarotips http://www.hungarotips.com/ - Poland
Poland (About.com) http://genealogy.about.com/od/poland/Polish_Genealogy_Family_History.htm
Poland (FamilySearch) https://www.familysearch.org/wiki/en/Poland_Genealogy
Poland GenWeb https://www.worldgenweb.net/poland/
Polish archives https://www.nac.gov.pl/en/digital-archive/szukajwarchiwach-pl-search-the-archives/
Polish archives (FamilySearch) https://www.familysearch.org/wiki/en/Poland_Holdings_of_the_Polish_State_Archives
Polish archives & JRI-Poland http://www.jewishgen.org/JRI-Pl/faq/intropsa.htm
Polish Jewish communities http://www.shabbat-goy.com/ (Shabbat Goy - site is in French but has a translate option on the front page)
Polish family resettlement camps in UK 1947-1969 http://www.polishresettlementcampsintheuk.co.uk/camps2.htm
Polish Genealogy (Facebook) https://www.facebook.com/groups/Polish.Genealogy
Polish Roots http://www.polishroots.org
Posen areas of Jewish genealogy https://www.jewishgen.org/infofiles/posenresources.html
Poznan Project http://poznan-project.psnc.pl (indexing marriages 1800-1899)
State Archives in Leszno https://www.ongenealogy.com/listings/state-archives-in-leszno/ - Romania
Romania Genealogy (FamilySearch) https://www.familysearch.org/wiki/en/Romania_Genealogy
Romania Resources https://feefhs.org/resource/romania
Romanian GenWeb https://www.worldgenweb.net/romania/ - Russia
Russia Genealogy (FEEFHS) https://feefhs.org/resource/russia-blitz-research
Russia Genealogy (FamilySearch) https://www.familysearch.org/wiki/en/Russia_Genealogy
Russia GenWeb https://www.worldgenweb.net/russia/
Russian Federation (Geneanet) https://en.geneanet.org/country/search-Russian%20Federation-RUS
Russian Links on the Web http://www.genealogylinks.net/europe/russia/ - Ukraine
How to Find Old Family Records in Ukraine https://lvivecotour.com/family-search-ukraine/how-to-find-old-family-records-in-ukraine/
Ukraine Genealogy (FamilySearch) https://www.familysearch.org/wiki/en/Ukraine_Genealogy
Ukrainian GenWeb https://www.worldgenweb.net/ukraine/
(The) Ukrainian History and Education Center https://www.ukrhec.org - (Former) Yugoslavia: Bosnia and Herzegovina, Croatia, Kosovo, Montenegro, North Macedonia, Serbia, Slovenia
Bosnia and Herzegovina Genealogy (FamilySearch) https://www.familysearch.org/wiki/en/Bosnia_and_Herzegovina_Genealogy
Bosnia and Herzegovina GenWeb https://www.worldgenweb.net/bosnia-herzegovina/
Croatian Archives Portal https://portal.ehri-project.eu/countries/hr
Croatian Genealogy http://www.appleby.net/genealogy.html
Croatian History Museum https://www.hismus.hr/en/
Kosovo Resources (FEEFHS) https://feefhs.org/resource/kosovo
Montenegro Genealogy (FamilySearch) https://www.familysearch.org/wiki/en/Montenegro_Genealogy
North Macedonia Genealogy (FamilySearch) https://www.familysearch.org/wiki/en/North_Macedonia_Genealogy
Serbia Genealogy (FamilySearch) https://www.familysearch.org/wiki/en/Serbia_Genealogy
Serbian Genealogy Society https://www.rodoslovlje.com
Slovenia Genealogy Links http://www.genealogylinks.net/europe/slovenia/index.html
Slovenia (The Family History Guide) https://www.thefhguide.com/project-9-slovenia.html - Eastern Europe (general)
Eastern Europe Genweb https://www.worldgenweb.net/links/eastern-europe-links/
East and Southeast European Archives https://www.ese-archives.geschichte.uni-muenchen.de
EuroDocs: Online Sources for European History http://eudocs.lib.byu.edu/index.php/Main_Page (selected transcriptions, facsimiles and translations)
European Genealogy Links Portal http://www.genealand.com/
Federation of East European Family History Societies http://www.feefhs.org
(The) Miriam Weiner Routes to Roots Foundation https://www.rtrfoundation.org/Archdta1.shtml (holdings and repositories in Eastern Europe)
See also Miscellaneous useful sites for international genealogy