The Cycles Encyclopedia by Frederik Steinmetz and Gottfried Hofmann from BlenderDiplom is the de-facto manual of the Cycles render engine.
On 360 pages (A4) it includes detailed descriptions of every Cycles node and setting and additional chapters showing the technical background of pathtracing render engines, ways to boost your render times and more.
The eBook comes in PDF format and is compatible with most e-reader devices, smartphones and tablets. The language of the eBook is English.
What do Blender users say about The Cycles Encyclopedia?
This book has been the result of an effort to bring Cycles material nodes closer to the Blender audience, and it is the best one hands down. - Spyros Mintzas, Blendernation
Very cool repository. It saved me hours of time in understanding cycles. And the best: updates for free! - Tobias Günther, elaspix
"The Cycles Encyclopedia" by Gottfriend Hofmann and Frederik Steinmetz is your definitive atlas for all things Cycles-related. Very handy and well-thought-out reference! - Reynante Martinez
If you want to know what any given Cycles node does (including input and output) without wading through a heap of tutorials, this is absolutely the resource you've been looking for. Bought a copy of this at BConf 2014 within minutes of it being announced and haven't been disappointed. Top work Gottfried Hofmann and Frederik Steinmetz! - S J Bennet
Excellent eBook, if you use Blender Cycles you probably need this book. - Terry Wallwork, Adventures in Blender
This encyclopedia will prove a very useful tool for me in the future and will save a lot of time. I would say that it will do the same for you, too, if you are a beginner, an experienced user or seasoned 3d user who wants to get into Blender and master the Cycles renderer. - James Abell