Voluntary health insurance in Europe: country experience
A long time has passed since WHO published a book on voluntary health insurance, just a decade (!). Therefore, there are many reasons to review again what's going on, and this is precisely what you'll find in two recent books.
Before any recommendation, it is good to have a good analysis. And the best analysis comes from reliable data. Somebody should check the published data in the book. In the case of Spain it says 10% of suplementary insurance, while it is around 16% (!) (p.50) (and it is duplicate really according to OECD classfication). And beyond that, it says that there is 3% of voluntary health insurance that is substitutive, while it is exactly 0% (!). Therefore take care. I'll not comment anything else.