If you want to go straight to the source, David Harel's "Statecharts: A Visual Formalism for Complex Systems" published in 1987 is the original paper: https://www.inf.ed.ac.uk/teaching/courses/seoc/2005_2006/res...
If you want to go straight to the source, David Harel's "Statecharts: A Visual Formalism for Complex Systems" published in 1987 is the original paper: https://www.inf.ed.ac.uk/teaching/courses/seoc/2005_2006/res...