John,

There are (at least) three other books that contain information that you will need:

"The Pilot's Handbook of Aeronautical Knowledge" FAA-H-8083-25B
"Risk Management Handbook" FAA-H-8083-2
"Aviation Weather Services" AC 00-45H

These are all referenced in the Glider Practical Test Standard (PTS) and should (will) be used by the examiner to develop questions and scenarios during the oral portion of your practical test.

The Glider PTS, FAA-S-8081-22.

All of these can be found, in PDF form with the current revision, on the FAA site.

https://www.faa.gov/ The search box is your friend!

Mike Bamberg
Glider DPE in the Portland Oregon area.