Wave Reference in Loop

Hello,

after making a global fit i have a lot of waves with the names Coef_xxx_sig0, Coef_xxx_sig1 .... Coef_xxx_sig80.

I want to use these waves/Coefficents in a procedure, but i struggle with the wave reference. I tried something like this:
    for(k=0;k<81;k+=1)
        String  wname = Coef_xxx_sig + num2str(k)
        wave $wname      
    endfor     


Can somebody help?

Thanks,
Wolf