The ninth entry in the official canon reference books known as the Star Wars Encyclopedia, titled "Lightsabers and Jedi Equipment," was released by Altaya in France and De Agostini in Spain. The primary subject of this issue is lightsabers.
In the English translation of the book, it is inaccurately written that Dooku's lightsaber contained a "Sith synthetic crystal." However, the original French version merely refers to it as a "Sith crystal."