Federal Board of the Free German Trade Union Federation
The Free German Trade Union Federation (Freier Deutscher Gewerkschaftsbund, FDGB) was the most significant mass organization in East Germany in terms of membership (over five million) and in terms of its power. The Federation was the only national trade union permitted in East Germany and it existed from 1946 until 1990 when East Germany was brought into the west. In addition to the FDGB being a trade union, it was a constituent member of the National Front of the German Democratic Republic (GDR/DDR), an alliance of political parties controlled by the Socialist Unity Party of Germany (SED), East Germany's ruling political party.
Winkler, H. A. (2007). Germany: The long road west. Oxford: Oxford University Press.
Campbell, J. (1992). European labor unions. New York: Greenwood Press. (Free German Trade Union Federation mentioned)
Sandford, G. W. (1983). From Hitler to Ulbricht: The communist reconstruction of East Germany, 1945-46. Princeton: Princeton University Press.
Encyclopediabritannica.com (Free German Trade Union Federation bio)