P. Borba.
" A Refinement Theory for Concurrent Object Oriented Languages", in <em>Anais do X Simpósio Brasileiro de Engenharia de Software</em>, São Carlos/SP, 1996, pp. 39-55, doi: <a href="https://doi.org/10.5753/sbes.1996.24436">https://doi.org/10.5753/sbes.1996.24436</a>.