Wei, Feng, Generalized Derivations with Nilpotent Values on Semiprime Rings, Acta mathematica Sinica. English series (Print) , 20(3), 2004, pp. 453-462
Let R be a semiprime ring, R F be its left Martindale quotient ring and I be an essential ideal of R. Then every generalized derivation defined on I can be uniquely extended to a generalized derivation of R F . Furthermore, if there exists a fixed positive integer n such that (x)n = 0 for all x I, then = 0.