1. Kranner, I., Minibayeva, F. V., Beckett, R. P. & Seal, C. E. (2010). What is Stress? Concepts, definitions, and applications in seed science. New Phytologist. 188: 655-673.
2. Edwards, J. (2015). Fundamental facts about mental health 2015, Mental Health Foundation, United Kingdom
3. Mallow M. S. (2016). Occupational Stress in Malaysia: Causes, Effects and Possible Solutions, In Proceedings of 3rd International Conference on Education, Social Sciences and Humanities (SOCIOINT 2016), 82-88, Istanbul, Turkey.
4. Poll H., American Psychological Association (APA) (2017). Stress in America: The state of our nation. Stress in America Survey.
5. Institute of Public Health (IPH), National Health and Morbidity Survey (2011). NHMS 2011, Vol. II: Non-communicable diseases, Ministry of Health Malaysia, ISBN: 978-967-3887-68-2.