Quote from their website:
The book was originally written in 2014 by MERG member, Davy Dick, and he has updated it in 2020. You can download each chapter using the links shown. There are just a few conditions:
- The book is intended as a service to the model railway community.
- It is not a commercial product.
- It is strictly a non-profit production.
- It must not be used for monetary gain.
- It is free to distribute and read.
- There will be no changes to book contents or its use without permission of the author.