A little tip for those of you that have Xrite calibration/profiling products and use i1profiler:
i1profiler uses a low-rez set of those roman16 images as part of its profile display/verification and you can access those images directly within the i1profiler program folder. On Windows, for example, they can be found in Program Files(x86)/X-Rite/i1Profiler/preview-images.
As I said, they are low-rez and don't include the technical details/numeric info that the full reference docs would include but they are still great references for experimenting and comparison-use for skin tones.