Ershov, A.P. et al "SIGMA, A Symbolic Generator and Macroassembler"

Bobrow, D. G. (ed) (1968) Bobrow, D. G. (ed) "Symbol Manipulation Languages and Techniques", Proceedings of the IFIP Working Conference on Symbol Manipulation Languages. North-Holland Publishing Co., Amsterdam, 1968  

Languages mentioned SIGMA {1968} BESM Macroprocessing system