Eeva Karttunen, Erkki Kuujo, Jorma Tiainen: Sortavalan kaupungin historia. Jyväskylä 1970.
Songbook with the lyrics and notation for the comrade song of Border Karelian Folk School from year 1921. Song was composed by Mikael Nyberg. Book was printed in Sortavala by Finnish Church’s local missionary society. The local missionary society was founded in Helsinki in 1905 and its central office was situated in Sortavala until 1939. Society’s mission was to improve the Deaconess Institution and to spread faith through printing. After the Second World War the society moved to Pieksämäki.