wrote Galois Theory of p-Extensions
comprising 204 pages back in 2002.
Textbook and eTextbook are published under ISBN 3540436294 and 9783540436294.
Since then Galois Theory of p-Extensions textbook
was available to sell back to BooksRun online for the top buyback price
or rent at the marketplace.
Helmut Koch's classic is now available in English. Competently translated by Franz Lemmermeyer, it introduces the theory of pro-p groups and their cohomology. The book contains a postscript on the recent development of the field written by H. Koch and F. Lemmermeyer, along with many additional recent references.