Inevitably, new material that is relevant to the book is appearing all the time, and errors that crept into the text are discovered.
Those who have a copy of the second printing (October 2014) may update their copy by removing the existing additional pages 237 and 238 from their copy with a sharp knife and inserting a double-sided print of the above file in their place.
Those who have a copy of the first printing (July 2014) may update their copy by manually making the changes in the book text given in the file below as well as inserting a double-sided print of the above file in the back of their copy.
Some extra references and websites that I have found since the publication of the Second Edition are given below.
Some extra items, to be added to the Revised Second Edition and the Additional Material for the earlier editions, are given below.
If you happen to find any errors (typographical or otherwise) in the book, please let me know!