The 'gap' between understanding of transistors and their application in real circuits
Buy this book The Art of Electronics by Horowitz and Hill (2nd edition). 

It cost $US20 (which is a bargain). It's in New Delhi and they have a number of them. If you cannot afford the 1050 Rupee get several friends to buy it together, This is the best book on the subject that you will find. 


The Art of Electronics (Second Edition)
(ISBN: 0521689171 )
Paul Horowitz,Winfield Hill
Bookseller: BookVistas (New Delhi, DEL, India)
Bookseller Rating:
Quantity Available: > 20  


WARNING" There are a lot of these also advertised in India. They cost typically the same or more as what I recommended and are not the same. Take due care. This the associated student manual by Horowitz and Hayes. If you can afford to buy one of these AS WELL do so but get the proper textbook first. Copy of workbook here for Rs484 including postage in India.