Three books for LibreOffice have been published by the LibreOffice Documentation team:
Getting Started with LibreOffice 3, January 2011, ISBN 978-1921320125.
LibreOffice 3 Writer Guide, April 2011, ISBN 978-1921320156.
LibreOffice 3 Calc Guide, June 2011, ISBN 978-1921320163.
PDFs and ODTs of the full books and of the individual chapters are available from this page. The printed editions are available from Lulu.com.