We welcome any report on errors (including very minor misprints) in the book as well as any other kind of comment - just send a mail to one of the authors.

On this page we list those mistakes which (1) are known to us and (2) in our opinion might cause some confusion to a reader.

- In Proposition (7.3), (2), on page 81,
*disc*has to be replaced by*det*. - The proof of Proposition (17.30) on page 276 is incorrect. For
a correct proof use the bijectivity of e
_{4}and [190, Theorem 4] or [148, Theorem 6.3], as mentioned in the text. - In the Index and in the Notation index the roman numeral page numbers i-xix have to be increased by ii.
- In Chap. VII, Exercise 10 (a), on page 444: The isomorphism takes [x,y] to x N(z) (mod squares). Its inverse takes x (mod squares) to [x,x].

Last error on this list added on 22 Dec 1998.

Here is another list of possible errors and other comments. It is merely an "unofficial" unedited stack of remarks and may contain erroneous items.

We warmly thank all contributors.

Last addition on July 31, 2013 or later.