https://www.guru99.com/software-testing-lifecycle.html
http://www.softwaretestingmentor.com/stlc-vs-sdlc/
https://www.tutorialspoint.com/stlc/stlc_sdlc_comparison.htm
http://www.softwaretestingstuff.com/2011/09/sdlc-vs-stlcdifferences-similarities.html
http://artoftesting.com/manualTesting/difference-between-sdlc-and-stlc.html
http://www.softwaretestingmentor.com/stlc-vs-sdlc/
https://www.tutorialspoint.com/stlc/stlc_sdlc_comparison.htm
http://www.softwaretestingstuff.com/2011/09/sdlc-vs-stlcdifferences-similarities.html
http://artoftesting.com/manualTesting/difference-between-sdlc-and-stlc.html