Hello Nuwan,
the 640-xxx exams have been retired long time ago
see
http://ciscocert.custhelp.com/app/answers/detail/a_id/3459/related/1/kw/retired%20exams/r_id/166
and notice no 640-901 existed.
Check the year the book has been published I think it is a typing error and the book should refer to new exam 642-901.
Be aware that several releses of the exams have been made so the book may refer not to the last version.
if you have an account on CCO you can easily get access to Cisco learning network
https://cisco.hosted.jivesoftware.com/community/certifications/ccnp/bsci?view=overview
where you can download the last blueprint for BSCI.
Compare it with the book index.
Cisco learning network can be helpful also for other reasons so I suggest to join it.
Edit:
I've just seen that you had opened another thread.
I agree with Mohamed that CiscoPress book is the best choice but other people has provided good reviews and impressions of the book from Lammie.
Hope to help
Giuseppe
