You can also order a $22.37 paperback from the author (via publish-on-demand site Lulu) from that same page, especially if you don't meet the terms of the limited license for the free download (as I read it, you won't qualify for the free download if you're using the book commercially, like for instance if you were wanting to distribute it to your paying students in a PDC course or something):
Any person, library, or organisation may download, print, photocopy or otherwise reproduce this book for purposes of private study, and do so free of legal or financial liability.
However, this book is copyrighted and may not be reproduced in any form for purposes of financial gain without prior permission in writing from the publisher, except by a reviewer who wishes to quote brief passages in connection with a review for inclusion in a journal, magazine, or newspaper. If a copy of this book is given free of charge to a third person then it must contain this copyright notice in full.
Anyone may download it, in pdf format, and may make an entirely voluntary contribution, by way of compensation to the author and publisher, via
www.sharebooks.ca on the internet.
You can find a donate button here, with an authorial pitch:
Donations: The authors have spent many years writing these books, and are giving them away for free. Donations are gratefully accepted.