If you can't find it, you can test it yourself. There are probably many different methods of doing so, you can probably find some online. The easiest would require a spring scale but if you don't have one you can find another method.
that's a really good idea. at least to get the coefficient of static friction.
i would suggest trying it with a few different weights on top of the paper, but if the coefficient of static friction remains constant, the angle of tilt (when sliding begins) should be the same, no matter what the weight is. the coefficient of static friction is a function of the angle of tilt.