This book is divided into two parts, and the main essence is concentrated in the first book. The content quality of the second volume is not as high as that of the first volume. The electronic version can't be found in the first volume (it is estimated that copyright protection is serious), and the electronic version can be found in the second volume. The landlord might as well borrow a paper version of the book from the library instead of searching the electronic version on the Internet, and he can scan and archive the important parts himself.