So far as I know, the oldest in the English language at least, is Banting's Letter on Corpulence. Having lost weight and dramatically improved his health on a low carbohydrate diet. Banting wrote and self-published the book back in the Mid-Victorian era, and he distributed it for free.
Read More »DaVinci Gourmet Sugar Free Syrups 50 ml bottles
DaVinci Gourmet Sugar Free Syrups 50 ml bottles
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