Most Lore and Legend Quests can be started either with a book or by examining one of the quest items. Find the book, Know Your Gnolls, using the location information above. Next, read the book, Know Your Gnolls, flip through all the pages, and accept the quest. Once you have accepted the quest you may place the book in your house. You do not need the book to progress the quest.
Steps
Find the following auto-updating pieces by killing Gnolls in any zone:
a gnoll spirit, a gnoll brain, a gnoll heart
Find and examine the following tradeable pieces obtained by looting Gnolls in any zone, or buying them from other players