"Is Proof More Cost-effective than Testing?"
a paper on CleanroomSoftwareEngineering atwww.sparkada.com:
http://www.praxis-his.com/pdfs/cost_effective_proof.pdf

This paper describes the use of CleanroomSoftwareEngineering practice on an industrial safety-critical application, where formal methods are required by UK law (?).

''[This paper referenced in CleanroomSoftwareEngineering discussion on CleanRoomSoftwareEngineeringIsNotDead page.]''