Filip van Laenen’s article in the ACCU magazine Overload provides another nice overview of mutation testing, looking mainly at Ruby, but with
some discussion of Java and PIT towards the end. Overload 108
The Overload 108 article is based on a presentation Filip van Laenen gave at OOP 2012 in Munich. The slides from that presentation can be viewed at SlideShare. Mutation Testing
An introduction to Mutation Testing, by Pedro Rijo, which contains the problem that Mutation Testing tries to solve, the presentation of the basic concepts, and a quick section on Extreme Mutation. Slides for the talk based on the article available at speakerdeck.