1. FDR2: a refinement checker for establishing properties of models expressed in CSP. www.fsel.com/software.html
2. SICStus prolog manual (arithmetic expressions). https://sicstus.sics.se/sicstus/docs/latest4/html/sicstus.html/ref_002dari_002daex.html#ref_002dari_002daex
3. The ProB animator and model checker. http://www.stups.uni-duesseldorf.de/ProB/index.php5/Main_Page
4. ISO/IEC: Information technology-Z formal specification notation-syntax, type system and semantics (2002). http://standards.iso.org/ittf/PubliclyAvailableStandards/c021573_ISO_IEC_13568_2002(E).zip
5. Abrial, J.R.: The B-book: Assigning Programs to Meanings. Cambridge University Press, Cambridge (2005)