Wendy01

I believe that all of the prep providers that are listed on the CFAI website (including Schweser, Stalla, Elan, etc) have signed an agreement with the CFAI that prevents them from promoting their products as a substitute for the CFAI materials, prevents them from advertising customer pass rates, etc.

http://www.cfainstitute.org/partners/examprep/Documents/cfa_prep_provider_guidelines_manual.pdf