1. https://www.statista.com/statistics/330695/number-of-smartphone-users-worldwide/)
2. https://gs.statcounter.com/os-market-share/mobile/
3. https://www.appbrain.com/stats/number-ofandroid-apps/
4. The rise of machine learning for detection and classification of malware: Research developments, trends and challenges by Gibert, D., Mateu, C
5. A Review of Android Malware Detection Approaches Based on Machine Learning