Walter Guttmann Helmuth Partsch Wolfram Schulte Ton Vullinghs Tool Support for the Interactive Derivation of Formally Correct Functional Programs. 173- 2003 9 J. UCS 2 http://www.jucs.org/jucs_9_2/tool_support_for_the db/journals/jucs/jucs9.html#GuttmannPSV03