ITIL® Book is actually a set of two volumes, one of service delivery and one of service support. ITIL® books have comprehensive information about the two service management domains of ITIL®. ITIL® book is just one of the way of getting information about ITIL® and knowing more about its framework and practices for better IT service management.
You can either get the published version or simply download the e-book version of ITIL® book, as is convenient and preferable. You can have the e-book version of ITIL® Book in pdf, word doc or ppt formats.
ITIL® Toolkit and BS15000 service management standards support the ITIL® Book information. Both the toolkit and the BS15000 standards are important to understand and effectively implement the information gathered from the ITIL® book.