(informal) As I found the business parts in this book were the most interesting part for me, it should be great for you to read when you get a downtime.

(semi-formal)IMHO, I would like you to take a moment to start the reading from the part of business in the book when you have a chance.

Of this book the business chapter is most useful. You might want to read the chapter as time allows.

I recommend that you read the business part of the book for your reference.