Correct, Pradeep. Since digital marketing is a dynamic field, there is always something new to learn. Books are our best friends and always have an upper hand in channelization of knowledge. However, choosing an apt book decides the path of your success.
Here's a list of best digital marketing books you should go through in the year 2016: http://www.digitalvidya.com/blog/10-must-read-digital-marketing-books-in-2016/
Would be glad to know which digital marketing book made you curious? For me, it is Youtility by Jay Baer.
I hope this helps