The book *
Funding a Revolution: Government Support for Computing Research*,
Committee on Innovations in Computing and Communications:
Lessons from History, National Research Council (U.S.A.),
National Academy Press, 302 pages, 1999, Chapter 8:
Theoretical Research:
Intangible Cornerstone of Computer Science, contains the following statement.
"The structured programming perspective led to a more advanced discipline, promulgated
by David Gries at Cornell University and Edsger Dijkstra at Eindhoven, which is
beginning to enter curricula. In this approach, programs are derived from specifications
by algebraic calculation. In the most advanced manifestation, formulated by Eric Hehner,
programming is identified with mathematical logic. Although it remains to be seen
whether this degree of mathematicization will eventually become common practice, the
history of engineering analysis suggests that this outcome is likely."

The most comprehensive source for data refinement is the 1998 book *Data Refinement: Model-Oriented Proof Methods and their
Comparison* by W.-P deRoever and
K.Engelhardt (Cambridge tracts in Theoretical Computer Science volume 47). On p.243
it says: "Rick Hehner is an expert on the simple formulation of program verification methods; his syntactic
characterization of L-simulation is the most elegant one we encountered."