 Complete the following phrase:  Grass Curtain was a quarterly journal of Southern Sudanese politics and current events published by the Southern Sudan Association in London between 1970 and 1972. Enoch Mading de Garang was the journals co-founder and editor-in-chief. The Grass Curtain was closely linked to the Southern Sudan Liberation Movement SSLM, the political arm of Anya-Nya, a collection of Southern Sudanese separatist movements formed during the First Sudanese Civil War. The journal was published in large part to generate wider support for the 