1. Android documentation.
https://developer.android.com/guide/components/activities/tasks-and-back-stack.html
2. Stackoverflow entry: Android singletask or singleinstance launch mode?
https://stackoverflow.com/questions/3219726/
3. Abdulla, P.A., Atig, M.F., Rezine, O., Stenman, J.: Multi-pushdown systems with budgets. In: Formal Methods in Computer-Aided Design (FMCAD), pp. 24–33 (2012)
4. Lecture Notes in Computer Science;A Bouajjani,1997
5. Breveglieri, L., Cherubini, A., Citrini, C., Crespi-Reghizzi, S.: Multi-push-down languages and grammars. Int. J. Found. Comput. Sci. 7(3), 253–292 (1996)