We can recommend the following books about BPMN:
|Jakob Freund, Bernd Rücker:
Our own publication which puts the emphasis on two areas:
The book is now also available in in Spanish.
BPMN 2.0 – Business Process Model and Notation
Books on Demand 2009 | Order at Amazon
A compact Introduction and reference work, which explains the symbols of BPMN with tangible examples.
BPMN Method and Style
Cody-Cassidy Press 2011 | Order at Amazon
Bruce Silver is a well known BPMN expert, especially in the USA. In his book he describes practical methodological approaches to create excellent BPMN process models. so far the book is only available in English but will soon be published in German (announced at the BPMN 2011 in Luzern).