The Contents are placed after the Preface.

The numbers in the right margin refer the page numbers of the original printed book, they appear just where the corresponding page begins, e.g., page 113 contains the text between “p. 113” and “p. 114”.

The footnotes have been placed at the end of the corresponding chapter or section, this may result in footnotes not appearing in the same page as in the printed book.

In the present edition some typographic errors or inconsistencies have been corrected. In the HTML version these corrections are marked with a dotted underline, and the printed text usually appears in a “pop-up hint” when hovering the cursor on it. Also marked in the same way are some possible mistakes that have not been corrected, the pop-up hint in this case explains the correct form.