Design By Contract

http://wiki.c2.com/?DesignByContractVsProgrammerTests

http://sett.ociweb.com/sett/settSep2011.html

https://news.ycombinator.com/item?id=7353767

https://www.eiffel.org/doc/eiffel/Examples

https://stackoverflow.com/questions/481312/why-is-design-by-contract-not-so-popular-compared-to-test-driven-development

http://se.inf.ethz.ch/people/ciupa/papers/esecfse07.pdf

http://se.ethz.ch/~meyer/publications/lncs/model_library.pdf

https://news.ycombinator.com/item?id=15384351

http://www.math.md/files/csjm/v25-n1/v25-n1-(pp44-74).pdf

https://www.bbv.ch/images/bbv/pdf/downloads/V2_Clean_Code_V3.pdf

http://prr.hec.gov.pk/jspui/bitstream/123456789/7454/1/wafa.basit.phd.thesis.pdf

https://gleichmann.wordpress.com/2007/12/09/test-driven-development-and-design-by-contract-friend-or-foe/