1) IGNOU School of Education 2005 Psychology of Development and Learning ES-332, Understanding the Learner as a Unique Individual, 2, IGNOU School of Education, pp 30-31.
2) Kalam, Apj Abdul, (2010), A Spirit of India, Reflecting the concerns, aspirations and dreams of the Indian youth, Rajpal &sons, Delhi, p187
3) Kalam, Apj Abdul, (2010), A Spirit of India, Reflecting the concerns, aspirations and dreams of the Indian youth, Rajpal &sons, Delhi, p112.
4) Kalam, Apj Abdul, (2014), Inspiring Thoughts, Rajpal &sons, Delhi, p46.