General versions for quadrics of Pascal and Brianchon theorems I am looking for a generalization to quadrics (with proofs) of Pascal's and Brianchon's theorems. It´s for Three dimensional analytical geometry.
I would be very thankful if you could point me towards one.

Tried to add this as a comment, but comments not working right now:
The question is an exact duplicate of this one.
But, anyway, start with the classical geometry texts. Salmon, Sommerville, and books like that. 
Sommerville, Analytical Geometry of Three Dimensions.
Snyder & Sisam, Analytical Geometry of Space
Salmon, A Treatise on the Analytic Geometry of Three Dimensions 
