From the introduction:
This tome is a record of my travels to other worlds and other planes, and an accounting of the various and interesting monsters I have encountered and brought back with me to populate my dungeon on Toril, known as the Ruins of Undermountain. In the pages to follow, the reader will find useful information concerning the origins, habitats, and abilities of these creatures.
Great care has been taken to supply an accurate description of these rare and wondrous beasts. However, not everything I know of them has been revealed. Reference this work at your own risk!
The PDF and HTML version contents are the same, but curiously not presented in the same order.