Bamboo and Exotic Wood Floors - heart pine installation

I have heart pine which was salvaged from old buildings and planed to 7/16" thick. The boards are not tongue and groove. I want to install these in my home on the concrete slab and am wondering what sort of adhesive to use. In the past I've seen this done but a 3/4" thick plywood sub-floor was glued to the concrete and the heart pine was then nailed to the ply wood. Some one has told me that there is a "thin set" glue that can be used directly on the concrete but I have no idea what that would be or where to find it. Can anyone advice me on the best way to install these heart pine floors? If there is such a "thin set" adhesive, what is the brand and where can I purchase it? These floors are absolutely beautiful when they are installed, sanded, poly coated with a couple of coats and then waxed. And, what I another thing that I loved about them is that you aren't supposed to mop them, EVER! :D I just want to make sure I install them correctly. Thanks for any input.