Efficient computation of expressions with common subexpressions. Ravi Sethi and Adrian Tang. Peter J. Downey, Ravi Sethi, and Robert Endre Tarjan. Variations on the common subexpression problem. E. G. Coffman, Jr. and Ravi Sethi.
Instruction sets for evaluating arithmetic expressions.
Jean-Claude Raoult and Ravi Sethi. Properties of a notation for combining functions.