Digital Signal Processing Technical Notes.
PureData and PlugData (vanilla) are, to the best of my knowledge, interchangeable for references. I just happen to prefer the look and feel of PlugData as a building environment.
PureData Quick Reference card (english PDF)
Introduction to Digital Filters with Audio Applications, Julius O. Smith III (external website)
Glossary of mathematical symbols (external website)
Pure Data Reference for Vanilla [rpole~ ] object. (external website)
University of California San Diego The Theory and Technique of Electronic Music and Filters in particular. (external website)
LTC 1060 - Data Sheet
AN24 - Unique Applications for the LTC1062 as a LPF
AN27 - A Simple Method of Designing Multiple Order All Pole BP Filters
AN40 - Take the Mystery Out of the SCF