Kothari, C. R. (1990). Research methodology: Methods and techniques (Second edition & Revised edition.). New Age; Wishwa Prakashan.

Kothari, C. R. Research Methodology: Methods and Techniques. Second edition & Revised edition. New Delhi: New Age; Wishwa Prakashan, 1990.

Kothari, C. R. Research Methodology: Methods and Techniques. Second edition & Revised edition. New Age; Wishwa Prakashan, 1990.