These works, the dBET PDF files, are provided free to you to download, print, and study, and otherwise use under the law.
Please note that the dBET PDFs have two copyright statements.
Copyright of dBET PDF File
This is the first copyright you will see and typically appears on the very first page of the PDF file, taking this form:
Copyright of Print Volume
The second copyright page you will see is a reproduction of the copyright from the print volume from which the PDF was made. Typically you will see it several pages into the book, taking this form:
Almost always the PDF is created and distributed some years after the print volume; hence the discrepancy in the copyright dates.