I'll show you!
I love these bookends except they slide. Their slick bottom is not ideal for holding books up. Since I had my stikkiwax out, I was able to put a pinch on the bottom of each and voile'.
Bookends that don't slide! Plus, with this stuff, I can move them around as needed and they'll still stick.
P.S. You can google stikkiwax for places to buy. I bought mine at our local school supply store and Amazon has them too.