Even though this is a thin book, this is packed with information - basically everything you need to get you started.
The author(s) talk about why people make sauerkraut/pickles, a little bit about their use in various ancient and more modern cultures and how pickles saved the sailors from scurvy starting with 18th century, when ships started carrying them.
Sauerkraut/pickles are fermented foods, and the fermentation happens because of lacto-bacteria (named like that because they were first discovered in milk/dairy products). Actually, there are two types of them: for milk products and for vegetables. Organic products have more bacteria and ferment easier. Raw (i.e. unpasterized) milk sours by itself; pasteurized milk spoils... The white film you can find on organic veggies (e.g. plums, cabbage) is lacto-bacteria. Those bacteria - and fermented products in general - are beneficial for digestion.
The best container for fermentation is Harsch - search the web to see it. I learned from this book that the white yeast that appears over open fermentation pots is actually harmless, just it has a bad taste.
It is easier to get better results with more veggies or with more types of plants versus one type only. Salt is needed for fermentation, authors say, to allow veggies to withstand a couple of days without decay until fermentation begins. If you have organic veggies, or good container (such as Harsch), there is less need for it. Whey could also be substituted, but not fully (i.e. you still need some salt).
What else is in the book? The spices, of course. And some therapeutical applications of pickles.
And, last but not least, some recipes that seem interesting to me.