20 December, annually International Human Solidarity Day
International Human Solidarity Day, article from Wikipedia     https://en.wikipedia.org/wiki/International_Human_Solidarity_Day

SOLIDARITY FOREVER   - Recordings by Pete Seeger, Utah Phillips, The Almanac Singers and many others on Youtube       https://www.youtube.com/results?search_query=solidarity+forever+song
Solidarity Forever, article from Wikipedia     https://en.wikipedia.org/wiki/Solidarity_Forever

SOLIDARITÄTSLIED  - Recordings by Ernst Busch, and others on Youtube       https://www.youtube.com/results?search_query=solidarit%C3%A4tslied
Solidaritätslied, article from Wikipedia     https://en.wikipedia.org/wiki/Solidarit%C3%A4tslied
FORWARD WE’VE NOT FORGOTTEN, "Solidaritätslied" in English     https://www.youtube.com/results?search_query=FORWARD+WE%E2%80%99VE+NOT+FORGOTTEN%2C