1. https://www.verywellhealth.com/four-phases-of-cardiac-rehabilitation-2696089

2. http://circ.ahajournals.org/content/57/3/549.abstract

3. none

4. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3116747/

5. https://www.healthline.com/health/what-are-mets#examples

6. none

7. none

8. none

9. none

10. https://www.healthline.com/health/what-are-mets#examples

11. https://www.heart.org/en/health-topics/heart-failure/what-is-heart-failure/classes-of-heart-failure

12. http://circ.ahajournals.org/content/101/7/828.full

13. none

14. none

15. none

16. none

17. none

18. https://www.webmd.com/diet/features/the-step-diet

19. none

20. http://emedicine.medscape.com/article/1827089-technique

21. http://emedicine.medscape.com/article/1827089-technique

22. http://emedicine.medscape.com/article/1827089-technique