От colar (10,492 – 1·11·37) 23.11.2008 (Обновление 3.0.3)
Ignore the drop rate, it does not factor in the fact you only get to loot it once. The book dropped for me after just 2 kills in ZD. And when I was running dungeon with a friend and 3 other pugged players, 3 more books dropped. I never saw it and never had a chance to roll on it since I was auto-passed. All 3 books dropped within 5 minutes of starting the dungeon and the 3 that needed it got it. Never saw any more after that so that suggests you only see it once when you loot it, you never get to loot it again.

 

The drop rate in ZD area may be around 30% based on how many mobs killed while in dungeon for the 3 that still needed it.

 

So ignore the abysmally low drop rate, get a friend or 2 if you're below 73, and have at least 390 first aid skill, no idea what is minimum to see it drop. Maybe just need to have the first aid training past 375?

 

От 250805 (550 – 1·1) 19.11.2008 (Обновление 3.0.3)
I can confirm 390 First Aid as being the apparent "required" skill level to have the book drop: I grinded on the aforementioned Drakuru Berserkers for about an hour at 382 First Aid and didn't see it drop. After leveling to 390, however, the book dropped on my third kill. This is consistent with what others are reporting.