Where are the "Digitized Kalmbach Media Books" on trains.com?

In the trains.com Unlimited “Member Benefits” promotional blurbware, there’s prominent mention of Digitized Kalmbach Media Books.

I can’t find any, except offers to buy Special Issues (and presumably one needn’t be a member to do so).

Has anyone found such an e-book anywhere? I’d like to maximize my member benefits.

Thanks!