1. 1. Park K. Preventive and Social Medicine.8thed. Bhanot publishers: 2005. p.13,15.
2. 2. Gulani KK. Community Health Nursing: Principles and Practices.18thed Kumar Publishing House:2008.p.11
3. 3. SuryaKantha AH. Community Medicine with recent Advances.1sted. Jaypee Publishers; 2009. p.7.
4. 4. Kishore J. National Health Programmes of India: National Policies and Legislation Related to Health. 8thed. Century Publications; 2009. p.191.
5. 5. Tahir M, Sharma SK, Rohrberg DS, Gupta D, Singh UB. DOTS at a tertiary care centre in Northern India: Successes, challenges and the Next Steps in Tuberculosis Control. Indian Journal of Medicine 2006;123(5):702-706