I need to buy an 11x17"Tracing Vellum pad know a reliable online source?

Answer 1

Three decades as a working visual artist qualify me to answer with confidence; Pearl Paint. Truly the most reliable, affordable, and largest source for artist's materials on line and offline.

http://www.pearlpaint.com/

Below is the their page for vellum pads.

http://www.pearlpaint.com/shop~ocID~6999~parentID~6999~categoryID~6946.htm