Elite Tomes Question

I've just started to farm some bosses in HM and killed a few of them 10 or so times, and have gotten no elite tomes.

So basically, I was just hoping to making get an insight into how often elite tomes really do drop for you guys

Thanks

From experience I can say it is a lot more likely a boss will drop his green than an elite tome.

How often they will drop anything of value depends on the boss. I can farm some and get a drop every 10 - 15 kills and others it will be more like 20 - 30+ kills to get something worth the time.

For me the green has dropped a lot more than the elite tome. Usually 15 times before i get something.

Tomes drop a little more for me in chests though.